If your family gets drinking water from a private well, do you know if your water is safe to drink? What health risks could you and your family face? Where can you go for help or advice? The EPA regulates public water systems; it does not have the authority to regulate private drinking water wells. Approximately 15% of Americans rely on their own private drinking water supplies, and these supplies are not subject to EPA standards, although some state and local governments do set rules to protect users of these wells. Unlike public drinking water systems serving many people, they do not have experts regularly checking the water’s source and its quality before it is sent to the tap. These households must take special precautions to ensure the protection and maintenance of their drinking water supplies.
 
Basic Information
 
There are three types of private drinking water wells: dug, driven, and drilled. Proper well construction and continued maintenance are keys to the safety of your water supply. Your state water-well contractor licensing agency, local health department, or local water system professional can provide information on well construction. The well should be located so rainwater flows away from it. Rainwater can pick up harmful bacteria and chemicals on the land’s surface. If this water pools near your well, it can seep into it, potentially causing health problems. Water-well drillers and pump-well installers are listed in your local phone directory. The contractor should be bonded and insured. Make certain your ground water contractor is registered or licensed in your state, if required. If your state does not have a licensing/registration program, contact the National Ground Water Association.

  

To keep your well safe, you must be sure that possible sources of contamination are not close by. Experts suggest the following distances as a minimum for protection — farther is better(see graphic on the right):

  • septic tanks:  50 feet;
  • livestock yards, silos, septic leach fields:  50 feet;
  • petroleum tanks, liquid-tight manure storage and fertilizer storage and handling:  100 feet; and 
  • manure stacks:  250 feet.

Many homeowners tend to forget the value of good maintenance until problems reach crisis-levels. That can be expensive. It’s better to maintain your well, find problems early, and correct them to protect your well’s performance. Keep up-to-date records of well installation and repairs, plus pumping and water tests. Such records can help spot changes and possible problems with your water system. If you have problems, ask a local expert to check your well construction and maintenance records. He or she can see if your system is okay or needs work.

Protect your own well area. Be careful about storage and disposal of household and lawn-care chemicals and wastes. Good farmers and gardeners minimize the use of fertilizers and pesticides. Take steps to reduce erosion and prevent surface water runoff. Regularly check underground storage tanks that hold home heating oil, diesel, or gasoline. Make sure your well is protected from the wastes of livestock, pets and wildlife.

 
Dug Wells
 

Dug wells are holes in the ground dug by shovel or backhoe. Historically, a dug well was excavated below the ground water table until incoming water exceeded the digger’s bailing rate. The well was then lined (cased) with stones, brick, tile, or other material to prevent collapse. It was covered with a cap of wood, stone or concrete. Since it is so difficult to dig beneath the ground water table, dug wells are not very deep. Typically, they are only 10 to 30 feet deep. Being so shallow, dug wells have the highest risk of becoming contaminated.To minimize the likelihood of contamination, your dug well should have certain features. These features help to prevent contaminants from traveling along the outside of the casing, or through the casing and into the well.

Dug Well Construction Features
  • The well should be cased with a watertight material (for example, tongue-and-groove pre-cast concrete), and a cement grout or bentonite clay sealant poured along the outside of the casing to the top of the well.
  • The well should be covered by a concrete curb and cap that stands about a foot above the ground.
  • The land surface around the well should be mounded so that surface water runs away from the well and is not allowed to pond around the outside of the wellhead.
  • Ideally, the pump for your well should be inside your home or in a separate pump house, rather than in a pit next to the well.

Land activities around a dug well can also contaminate it. While dug wells have been used as a household water supply source for many years, most are relics of older homes, dug before drilling equipment was readily available, or when drilling was considered too expensive. If you have a dug well on your property and are using it for drinking water, check to make sure it is properly covered and sealed. Another problem relating to the shallowness of a dug well is that it may go dry during a drought when the ground water table drops.

 
Driven Wells  
  
Like dug wells, driven wells pull water from the water-saturated zone above the bedrock. Driven wells can be deeper than dug wells. They are typically 30 to 50 feet deep and are usually located in areas with thick sand and gravel deposits where the ground water table is within 15 feet of the ground’s surface. In the proper geologic setting, driven wells can be easy and relatively inexpensive to install. Although deeper than dug wells, driven wells are still relatively shallow and have a moderate-to-high risk of contamination from nearby land activities.
Driven Well Construction Features
  • Assembled lengths of 2- to 3-inch diameter metal pipes are driven into the ground. A screened “well point” located at the end of the pipe helps drive the pipe through the sand and gravel. The screen allows water to enter the well and filters out sediment.
  • The pump for the well is in one of two places: on top of the well, or in the house. An access pit is usually dug around the well down to the frost line, and a water discharge pipe to the house is joined to the well pipe with a fitting.
  • The well and pit are capped with the same kind of large-diameter concrete tile used for a dug well. The access pit may be cased with pre-cast concrete.

To minimize this risk, the well cover should be a tight-fitting concrete curb and cap with no cracks, and should sit about a foot above the ground. Slope the ground away from the well so that surface water will not pond around the well. If there’s a pit above the well, either to hold the pump or to access the fitting, you may also be able to pour a grout sealant along the outside of the well pipe. Protecting the water quality requires that you maintain proper well construction and monitor your activities around the well. It is also important to follow the same land-use precautions around the driven well as described under dug wells.

Drilled Wells

 

Drilled wells penetrate about 100 to 400 feet into the bedrock. Where you find bedrock at the surface, it is commonly called ledge. To serve as a water supply, a drilled well must intersect bedrock fractures containing ground water.

Drilled Well Construction Features

  • The casing is usually metal or plastic pipe, 6 inches in diameter, that extends into the bedrock to prevent shallow ground water from entering the well. By law, the casing has to extend at least 18 feet into the ground, with at least 5 feet extending into the bedrock. The casing should also extend a foot or two above the ground’s surface. A sealant, such as cement grout or bentonite clay, should be poured along the outside of the casing to the top of the well. The well should be capped to prevent surface water from entering the well.

  • Submersible pumps, located near the bottom of the well, are most commonly used in drilled wells. Wells with a shallow water table may feature a jet pump located inside the home. Pumps require special wiring and electrical service. Well pumps should be installed and serviced by a qualified professional registered with your state.

  • Most modern drilled wells incorporate a pitless adapter designed to provide a sanitary seal at the point where the discharge water line leaves the well to enter your home. The device attaches directly to the casing below the frost line, and provides a watertight sub-surface connection, protecting the well from frost and contamination.

  • Older drilled wells may lack some of these sanitary features. The well pipe used was often 8, 10 or 12 inches in diameter, and covered with a concrete well cap either at or below the ground’s surface. This outmoded type of construction does not provide the same degree of protection from surface contamination. Also, older wells may not have a pitless adapter to provide a seal at the point of discharge from the well.

Hydrofracting a Drilled Well

 

Hydrofracting is a process that applies water or air under pressure into your well to open up existing fractures near your well, and can even create new ones. Often, this can increase the yield of your well. This process can be applied to new wells with insufficient yield and to improve the quantity of older wells.

How can I test the quality of my private drinking water supply? 
Consider testing your well for pesticides, organic chemicals, and heavy metals before you use it for the first time. Test private water supplies annually for nitrate and coliform bacteria to detect contamination problems early. Test them more frequently if you suspect a problem. Be aware of activities in your watershed that may affect the water quality of your well, especially if you live in an unsewered area.
 
Human Health
 

The first step to protect your health and the health of your family is learning about what may pollute your source of drinking water. Potential contamination may occur naturally, or as a result of human activity.

What are some naturally occurring sources of pollution?
  • micro-organisms:  Bacteria, viruses, parasites and other microorganisms are sometimes found in water. Shallow wells — those with water close to ground level — are at most risk. Runoff, or water flowing over the land surface, may pick up these pollutants from wildlife and soils. This is often the case after flooding. Some of these organisms can cause a variety of illnesses. Symptoms include nausea and diarrhea. These can occur shortly after drinking contaminated water. The effects could be short-term yet severe (similar to food poisoning), or might recur frequently or develop slowly over a long time.
  • radionuclides: Radionuclides are radioactive elements, such as uranium and radium. They may be present in underlying rock and ground water.
  • radon: Radon is a gas that is a natural product of the breakdown of uranium in the soil and can also pose a threat. Radon is most dangerous when inhaled, and contributes to lung cancer. Although soil is the primary source, using household water containing radon contributes to elevated indoor radon levels. Radon is less dangerous when consumed in water, but remains a risk to health.
  • nitrates and nitrites: Although high nitrate levels are usually due to human activities (see below), they may be found naturally in ground water. They come from the breakdown of nitrogen compounds in the soil. Flowing ground water picks them up from the soil. Drinking large amounts of nitrates and nitrites is particularly threatening to infants (for example, when mixed in formula).
  • heavy metals: Underground rocks and soils may contain arsenic, cadmium, chromium, lead, and selenium. However, these contaminants are not often found in household wells at dangerous levels from natural sources.
  • fluoride: Fluoride is helpful in dental health, so many water systems add small amounts to drinking water. However, excessive consumption of naturally occurring fluoride can damage bone tissue. High levels of fluoride occur naturally in some areas. It may discolor teeth, but this is not a health risk.

What human activities can pollute ground water?

  • Septic tanks are designed to have a leach field around them, which is an area where wastewater flows out of the tank. This wastewater can also move into the ground water.
    bacteria and nitrates: These pollutants are found in human and animal wastes. Septic tanks can cause bacterial and nitrate pollution. So can large numbers of farm animals. Both septic systems and animal manure must be carefully managed to prevent pollution. Sanitary landfills and garbage dumps are also sources. Children and some adults are at higher risk when exposed to waterborne bacteria. These include the elderly and people whose immune systems are weak due to AIDS or treatments for cancer. Fertilizers can add to nitrate problems. Nitrates cause a health threat in very young infants called “blue baby syndrome." This condition disrupts oxygen flow in the blood. 

  • concentrated animal feeding operations (CAFOs): The number of CAFOs, often called “factory farms,” is growing. On these farms, thousands of animals are raised in a small space. The large amounts of animal waste/manure from these farms can threaten water supplies. Strict and careful manure management is needed to prevent pathogen and nutrient problems. Salts from high levels of manure can also pollute ground water. 

  • heavy metals: Activities such as mining and construction can release large amounts of heavy metals into nearby ground water sources. Some older fruit orchards may contain high levels of arsenic, once used as a pesticide. At high levels, these metals pose a health risk. 

  • fertilizers and pesticides: Farmers use fertilizers and pesticides to promote growth and reduce insect damage. These products are also used on golf courses and suburban lawns and gardens. The chemicals in these products may end up in ground water. Such pollution depends on the types and amounts of chemicals used and how they are applied. Local environmental conditions (soil types, seasonal snow and rainfall) also affect this pollution. Many fertilizers contain forms of nitrogen that can break down into harmful nitrates. This could add to other sources of nitrates mentioned above. Some underground agricultural drainage systems collect fertilizers and pesticides. This polluted water can pose problems to ground water and local streams and rivers. In addition, chemicals used to treat buildings and homes for termites and other pests may also pose a threat. Again, the possibility of problems depends on the amount and kind of chemicals. The types of soil and the amount of water moving through the soil also play a role. 

  • industrial products and waste: Many harmful chemicals are used widely in local business and industry. These can pollute drinking water if not well-managed. The most common sources of such problems are:
    • local businesses: These include nearby factories, industrial plants, and even small businesses such as gas stations and dry cleaners. All handle a variety of hazardous chemicals that need careful management. Spills and improper disposal of these chemicals and other industrial wastes can threaten ground water supplies.
    • leaking underground tanks and piping: Petroleum products, chemicals and waste stored in underground storage tanks and pipes may end up in the ground water. Tanks and piping leak if they are constructed or installed improperly. Steel tanks and piping corrode with age. Tanks are often found on farms. The possibility of leaking tanks is great on old, abandoned farm sites. Farm tanks are exempt from the EPA rules for petroleum and chemical tanks.
    • landfills and waste dumps: Modern landfills are designed to contain any leaking liquids. But floods can carry them over the barriers. Older dumpsites may have a wide variety of pollutants that can seep into ground water.

  • household waste: Improper disposal of many common products can pollute ground water. These include cleaning solvents, used motor oil, paints, and paint thinners. Even soaps and detergents can harm drinking water. These are often a problem from faulty septic tanks and septic leaching fields. 

  • lead and copper: Household plumbing materials are the most common source of lead and copper found in home drinking water. Corrosive water may cause metals in pipes or soldered joints to leach into your tap water. Your water’s acidity or alkalinity (often measured as pH) greatly affects corrosion. Temperature and mineral content also affect how corrosive it is. They are often used in pipes, solder and plumbing fixtures. Lead can cause serious damage to the brain, kidneys, nervous system, and red blood cells. The age of plumbing materials — in particular, copper pipes soldered with lead — is also important. Even in relatively low amounts, these metals can be harmful. The EPA rules under the Safe Drinking Water Act limit lead in drinking water to 15 parts per billion. Since 1988, the Act allows only lead-free pipe, solder and flux in drinking water systems. The law covers both new installations and repairs of plumbing.
 What You Can Do...

 

Private, individual wells are the responsibility of the homeowner. To help protect your well, here are some steps you can take:

Have your water tested periodically. It is recommended that water be tested every year for total coliform bacteria, nitrates, total dissolved solids, and pH levels. If you suspect other contaminants, test for those. Always use a state-certified laboratory that conducts drinking water tests. Since these can be expensive, spend some time identifying potential problems. Consult your InterNACHI inspector for information about how to go about water testing.

Testing more than once a year may be warranted in special situations if:

  • someone in your household is pregnant or nursing;
  • there are unexplained illnesses in the family;
  • your neighbors find a dangerous contaminant in their water;
  • you note a change in your water's taste, odor, color or clarity;
  • there is a spill of chemicals or fuels into or near your well; or 
  • you replace or repair any part of your well system.

Identify potential problems as the first step to safe-guarding your drinking water. The best way to start is to consult a local expert -- someone who knows your area, such as the local health department, agricultural extension agent, a nearby public water system, or a geologist at a local university. 


Be aware of your surroundings. As you drive around your community, take note of new construction. Check the local newspaper for articles about new construction in your area.

Check the paper or call your local planning and zoning commission for announcements about hearings or zoning appeals on development or industrial projects that could possibly affect your water. 


Attend these hearings, ask questions about how your water source is being protected, and don't be satisfied with general answers.  Ask questions, such as:  "If you build this landfill, what will you do to ensure that my water will be protected?" See how quickly they answer and provide specifics about what plans have been made to specifically address that issue.

Identify Potential Problem Sources

To start your search for potential problems, begin close to home. Do a survey around your well to discover:

  • Is there livestock nearby?
  • Are pesticides being used on nearby agricultural crops or nurseries?
  • Do you use lawn fertilizers near the well?
  • Is your well downstream from your own or a neighbor's septic system?
  • Is your well located near a road that is frequently salted or sprayed with de-icers during winter months?
  • Do you or your neighbors dispose of household waste or used motor oil in the backyard, even in small amounts?

If any of these items apply, it may be best to have your water tested and talk to your local public health department or agricultural extension agent to find ways to change some of the practices which can affect your private well.

 
In addition to the immediate area around your well, you should be aware of other possible sources of contamination that may already be part of your community or may be moving into your area. Attend any local planning or appeals hearings to find out more about the construction of facilities that may pollute your drinking water. Ask to see the environmental impact statement on the project. See if the issue of underground drinking water sources has been addressed. If not, ask why.
 

Common Sources of Ground Water Contamination

Category        Contaminant Source
Agricultural
  • animal burial areas
  • drainage fields/wells
  • animal feedlots
  • irrigation sites
  • fertilizer storage/use
  • manure spreading areas/pits, lagoons
  • pesticide storage/use
Commercial
  • airports
  • jewelry/metal plating
  • auto repair shops
  • laundromats
  • boat yards
  • medical institutions
  • car washes
  • paint shops
  • construction areas
  • photography establishments
  • cemeteries
  • process waste-water drainage
  • dry cleaners fields/wells
  • gas stations
  • railroad tracks and yards
  • golf courses
  • research laboratories
  • scrap and junkyards
  • storage tanks
Industrial
  • asphalt plants
  • petroleum production/storage
  • chemical manufacture/storage
  • pipelines
  • electronic manufacture
  • process waste-water drainage
  • electroplaters fields/wells
  • foundries/metal fabricators
  • septage lagoons and sludge
  • machine/metalworking shops
  • storage tanks
  • mining and mine drainage
  • toxic and hazardous spills
  • wood-preserving facilities
Residential
  • fuel oil
  • septic systems, cesspools
  • furniture stripping/refinishing
  • sewer lines
  • household hazardous products
  • swimming pools (chemicals)
  • household lawns
Other
  • hazardous waste landfills
  • recycling/reduction facilities
  • municipal incinerators
  • road de-icing operations
  • municipal landfills
  • road maintenance depots
  • municipal sewer lines
  • Storm water drains/basins/wells
  • open burning sites
  • transfer stations

 

 

 
 
 
Septic systems treat and disperse relatively small volumes of wastewater from individual and small numbers of homes and commercial buildings. Septic system regulation is usually a state and local responsibility. The EPA provides information to homeowners and assistance to state and local governments to improve the management of septic systems to prevent failures that could harm human health and water quality.   
 
Information for Homeowners

If your septic tank failed, or you know someone whose did, you are not alone. As a homeowner, you are responsible for maintaining your septic system. Proper septic system maintenance will help keep your system from failing and will help maintain your investment in your home. Failing septic systems can contaminate the ground water that you and your neighbors drink and can pollute nearby rivers, lakes and coastal waters.

 Ten simple steps you can take to keep your septic system working properly:
  1. Locate your septic tank and drainfield. Keep a drawing of these locations in your records.
  2. Have your septic system inspected at least every three years. Hire an InterNACHI inspector trained in septic inspections. 
  3. Pump your septic tank as needed (generally, every three to five years).
  4. Don't dispose of household hazardous waste in sinks or toilets.
  5. Keep other household items, such as dental floss, feminine hygiene products, condoms, diapers, and cat litter out of your system.
  6. Use water efficiently.
  7. Plant only grass over and near your septic system. Roots from nearby trees or shrubs might clog and damage the system. Also, do not apply manure or fertilizers over the drainfield.
  8. Keep vehicles and livestock off your septic system. The weight can damage the pipes and tank, and your system may not drain properly under compacted soil.
  9. Keep gutters and basement sump pumps from draining into or near your septic system.
  10. Check with your local health department before using additives. Commercial septic tank additives do not eliminate the need for periodic pumping and can be harmful to your system.
How does it work? 
 
A typical septic system has four main components: a pipe from the home, a septic tank, a  drainfield, and the soil. Microbes in the soil digest and remove most contaminants from wastewater before it eventually reaches groundwater. The septic tank is a buried, watertight container typically made of concrete, fiberglass, or polyethylene. It holds the wastewater long enough to allow solids to settle out (forming sludge), and oil and grease to float to the surface (as scum). It also allows partial decomposition of the solid materials. Compartments and a T-shaped outlet in the septic tank prevent the sludge and scum from leaving the tank and traveling into the drainfield area. Screens are also recommended to keep solids from entering the drainfield. The wastewater exits the septic tank and is discharged into the drainfield for further treatment by the soil. Micro-organisms in the soil provide final treatment by removing harmful bacteria, viruses and nutrients.
 

Your septic system is your responsibility!

Did you know that, as a homeowner, you’re responsible for maintaining your septic system? Did you know that maintaining your septic system protects your investment in your home? Did you know that you should periodically inspect your system and pump out your septic tank? If properly designed, constructed and maintained, your septic system can provide long-term, effective treatment of household wastewater. If your septic system isn’t maintained, you might need to replace it, costing you thousands of dollars. A malfunctioning system can contaminate groundwater that might be a source of drinking water. And if you sell your home, your septic system must be in good working order.
 
Pump frequently...
You should have your septic system inspected at least every three years by a professional, and have your tank pumped as necessary (generally every three to five years).
 
Use water efficiently...
Average indoor water use in the typical single-family home is almost 70 gallons per person per day. Dripping faucets can waste about 2,000 gallons of water each year. Leaky toilets can waste as much as 200 gallons each day. The more water a household conserves, the less water enters the septic system.
 
Flush responsibly... 
Dental floss, feminine hygiene products, condoms, diapers, cotton swabs, cigarette butts, coffee grounds, cat litter, paper towels, and other kitchen and bathroom waste can clog and potentially damage septic system components. Flushing household chemicals, gasoline, oil, pesticides, anti-freeze and paint can stress or destroy the biological treatment taking place in the system, as well as contaminate surface waters and groundwater.
 
How do I maintain my septic system?
  • Plant only grass over and near your septic system. Roots from nearby trees or shrubs might clog and damage the drainfield.
  • Don’t drive or park vehicles on any part of your septic system. Doing so can compact the soil in your drainfield or damage the pipes, the tank or other septic system components.
  • Keep roof drains, basement sump pump drains, and other rainwater and surface water drainage systems away from the drainfield. Flooding the drainfield with excessive water slows down or stops treatment processes and can cause plumbing fixtures to back up. 
Why should I maintain my septic system?
 
A key reason to maintain your septic system is to save money! Failing septic systems are expensive to repair or replace, and poor maintenance is often the culprit. Having your septic system inspected (at least every three years) is a bargain when you consider the cost of replacing the entire system. Your system will need pumping every three to five years, depending on how many people live in the house and the size of the system. An unusable septic system or one in disrepair will lower your property’s value and could pose a legal liability. Other good reasons for safe treatment of sewage include preventing the spread of infection and disease, and protecting water resources. Typical pollutants in household wastewater are nitrogen phosphorus, and disease-causing bacteria and viruses. Nitrogen and phosphorus are aquatic plant nutrients that can cause unsightly algae blooms. Excessive nitrate-nitrogen in drinking water can cause pregnancy complications, as well as methemoglobinemia (also known as "blue baby syndrome") in infancy. Pathogens can cause communicable diseases through direct or indirect body contact, or ingestion of contaminated water or shellfish. If a septic system is working properly, it will effectively remove most of these pollutants.
 
 
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Soil is a naturally-occurring mixture of mineral and organic ingredients with a definite form, structure, and composition. It’s composed primarily of minerals which are produced from parent material which is broken into small pieces by weathering. Larger pieces are stones, gravel, and other rock debris. Smaller particles are sand, silt, or clay. Since the original materials vary from place to place, the exact composition of soil varies according to location. A common example of soil composition by volume might be:

  • 45% Minerals (clay, silt, sand, gravel, stones).
  • 25% Water (the amount varies depending upon precipitation and the water-holding capacity of the soil).
  • 25% Air (an essential ingredient for living organisms).
  • 5% Organic matter or humus (both living and dead organisms).

Mineral particles give soil texture. Sand particles range in diameter from 2 mm to 0.05 mm, feel gritty and can be easily seen with the unaided eye. Silt particles are between 0.05 mm and 0.002 mm and feel like flour. Clay particles are smaller than 0.002 mm and cannot be seen with the unaided eye. Because of the small particle size, clay soils can sometimes experience large amounts of expansion and contraction in volume with changes in moisture content.

Water and air occupy the pore spaces—the area between soil particles. The final ingredient of a soil is organic matter. Organic matter consists of dead plant and animal material and the billions of living organisms that inhabit soil.

The concern with soil in respect to building is the ability of soil to bear the load of the structure while remaining stable. Ensuring long-term stability requires proper compaction and consolidation of soil before a permanent load is placed upon it. Examples of a permanent load would be foundation footings and walls or a concrete floor or driveway slab.

The excavation process disturbs soil, loosening it and causing spaces between soil particles to become much larger. For this reason, engineering specifications often require that foundations be placed on undisturbed soil. 

In areas at which a home is built partially or completely on fill, such as homes built on hillsides, that fill must be made as solid as possible before a permanent load is placed on it. This is done by mechanical compaction of the soil. Soil is placed in layers (called “lifts”). Each layer is mechanically compacted by impact and sometimes by vibration.

When larger areas such as a hillside lot are compacted, heavy equipment is used. For smaller areas like backfill around basement foundation walls, a jumping jack tamper is used which is operated by one person. 

Compaction is the process of forcing air from the spaces between soil particles. Compaction with a jumping jack tamper is somewhat inexact. In determining the point at which soil is adequately compacted, the operator listens to the tone of the tamper impacting the soil. When soil is adequately compacted, the tone will have a ringing quality which will not change. A change in tone indicates that compaction is still taking place.

Compaction increases the density of the soil and improves its ability to bear a load. Compaction is affected by a number of factors:

  • Soil type (clay, sand, silt, level of organic matter, etc.)
  • Soil characteristics (uniformity, gradient, plasticity, etc.)
  • Soil thickness
  • Method of compaction
  • Moisture content at the time of compaction.

Consolidation is the process of forcing water from the spaces between soil particles. Soil is more permeable to air than to water. This means that the compaction process may remove from the soil a large percentage of air, but a significant percentage of water may remain. 

Soil undergoes both primary and secondary consolidation.
Primary consolidation is short-term and takes place during the mechanical compacting process. Secondary consolidation is long-term and takes place after the compaction process is complete and the permanent loads are in place. 

During secondary consolidation, the weight placed on soil slowly forces water out of the spaces between soil particles. As this happens, soil particles will move close together and settling will occur. The source of the weight would be both the structure and the overlying soil.

The amount of secondary consolidation which can be expected increases with the depth of the affected area. An excavation with backfill 15 feet deep would experience more secondary consolidation than an excavation with backfill 8 feet deep.

A common scenario is when a structure is built partially on undisturbed soil and partially on compacted fill. Soil in these two areas will consolidate at different rates as the weight of the newly-built structure forces water from between soil particles. This is called “differential settlement”.

Settling will be reflected in any part of structure bearing upon the settled soil. In adequately-compacted soil, settling will be so minor that evidence won’t be visible. Extreme differential settlement will create stresses which are relieved by cracking. 

Which materials crack depends on the properties of the material and the rate of settling. More brittle materials will crack first. The effects of soil movement are most often seen as cracks in interior and exterior wall coverings like drywall and plaster and in masonry foundation walls.

Even concrete, which most people think of as brittle, can bend if pressure is applied slowly over a long time period. If pressure is applied over a shorter time period, concrete will crack.

Compaction and consolidation are affected by the composition of the soil. Fine-grained soils have more interior surface area and can hold more air and water than course-grained soils. 
 
Here's an example. Drywall is made of much courser particles than cement. An ounce of drywall dust contains about 5,000 square feet of interior surface area. An ounce of cement dust contains about 50,000 square feet of interior surface area.
 
This means that fine-grained soils like clays have more interior surface area which can contain water. In order to force water out of the spaces between particles, surface tension must be overcome. "Surface tension" is the tendency of water to cling to a surface. When you fill a glass with water, it's surface tension that makes the water level slightly higher around the edges where water comes into contact with the glass surface. Water is clinging to the glass.
 
The greater interior surface area of fine-grained soils results in greater surface tension. Fine-grained are also typically low-permeability soils, meaning that water moves through them slowly. These conditions increase the amount of time and pressure required for soil to consolidate. Soils will continue to consolidate until the resistance to pressure of the materials of which the soil is composed reach equilibrium with pressure from the weight of soil and structure above.

The rate of consolidation is affected by the soil composition, levels of moisture saturation, the amount and nature of the load on the soil and state of consolidation of the soil.

Another moisture-related problem is the addition of excessive moisture to the soil. This can create a condition in which water is absorbed into spaces between soil particles. Soil becomes less dense, which reduces its ability to support a load.
 

The following chart details the predicted life expectancy of appliances, products, materials, systems and components. 
 
Consumers and inspectors and other professionals advising their clients should note that these life expectancies have been determined through research and testing based on regular recommended maintenance and conditions of normal wear and tear, and not extreme weather (or other) conditions, neglect, over-use or abuse.  Therefore, they should be used as guidelines only, and not relied upon as guarantees or warranties. 
 
*********************************************************************** 
Surface preparation and paint quality are the most important determinants of a paint's life expectancy. Ultraviolet (UV) rays via sunshine can shorten life expectancy.  Additionally, conditions of high humidity indoors or outdoors can affect the lifespan of these components, which is why they should be inspected and maintained seasonally.
 
ADHESIVES, CAULK & PAINTS
YEARS
Caulking (interior & exterior)
5 to 10
Construction Glue
20+
Paint (exterior)
7 to 10
Paint (interior)
10 to 15
Roofing Adhesives/Cements
15+
Sealants
8
Stains
3 to 8
 
 
Appliance life expectancy depends to a great extent on the use it receives. Furthermore, consumers often replace appliances long before they become worn out due to changes in styling, technology and consumer preferences.
 
APPLIANCES      
YEARS
Air Conditioner (window)
5 to 7
Compactor (trash)
6
Dehumidifier
8
Dishwasher
9
Disposal (food waste)
12
Dryer Vent  (plastic)
5
Dryer Vent  (steel)
20
Dryer (clothes)
13
Exhaust Fans
10
Freezer   
10 to 20
Gas Oven
10 to 18
Hand Dryer
10 to 12
Humidifier (portable)
8
Microwave Oven
9
Range/Oven Hood
14
Electric Range
13 to 15
Gas Range   
15 to 17
Refrigerator
9 to 13
Swamp Cooler
5 to 15
Washing Machine
5 to 15
Whole-House Vacuum System
20
 
 
 
Modern kitchens today are larger and more elaborate.  Together with the family room, they now form the “great room.” 
 
CABINETRY & STORAGE   
YEARS
Bathroom Cabinets 
50+ 
Closet Shelves  100+
Entertainment Center/Home Office 10
Garage/Laundry Cabinets 70+
Kitchen Cabinets 50
Medicine Cabinet 25+
Modular (stock manufacturing-type)
50 
 
 
Walls and ceilings last the full lifespan of the home.
 
CEILINGS & WALLS
YEARS
Acoustical Tile Ceiling
40+ (older than 25 years may contain asbestos)
Ceramic Tile   
70+
Concrete
75+
Gypsum
75
Wood Paneling
20 to 50
Suspended Ceiling
25+
 
 
Natural stone countertops, which are less expensive than they were just a few years ago, are becoming more popular, and one can expect them to last a lifetime. Cultured marble countertops have a shorter life expectancy, however.
 
COUNTERTOPS
YEARS
Concrete
50
Cultured Marble   
20
Natural Stone
100+
Laminate
20 to 30
Resin
10+
Tile
100+
Wood
100+
 
 
Decks are exposed to a wide range of conditions in different climates, from wind and hail in some areas, to relatively consistent, dry weather in others. See FASTENERS & STEEL section for fasteners.
 
DECKS
YEARS 
Deck Planks
15
Composite
8 to 25
Structural Wood
10 to 30
 
 
Exterior fiberglass, steel and wood doors will last as long as the house, while vinyl and screen doors have a shorter life expectancy. The gaskets/weatherstripping of exterior doors may have to be replaced every 5 to 8 years.
 
DOORS
YEARS
Closet (interior) 
100+
Fiberglass (exterior) 
100+
Fire-Rated Steel (exterior)
100+
French (interior) 
30 to 50
Screen (exterior)
30
Sliding Glass/Patio (exterior)
20 (for roller wheel/track repair/replacement)
Vinyl (exterior) 20
Wood (exterior)
100+
Wood (hollow-core interior)
20 to 30
Wood (solid-core interior)
30 to 100+
 
 
Copper-plated wiring, copper-clad aluminum, and bare copper wiring are expected to last a lifetime, whereas electrical accessories and lighting controls, such as dimmer switches, may need to be replaced after 10 years.  GFCIs could last 30 years, but much less if tripped regularly.
 
Remember that faulty, damaged or overloaded electrical circuits or equipment are the leading cause of house fires, so they should be inspected regularly and repaired or updated as needed.
 
ELECTRICAL
YEARS
Accessories
10+
Arc-Fault Circuit Interrupters (AFCIs)
30
Bare Copper
100+
Bulbs (compact fluorescent)
8,000 to 10,000+ hours
Bulbs (halogen)
4,000 to 8,000+ hours
Bulbs (incandescent)
1,000 to 2,000+ hours
Bulbs (LED)
30,000 to 50,000+ hours
Copper-Clad Aluminum
100+
Copper-Plated
100+
Fixtures
40
Ground-Fault Circuit Interrupters (GFCIs)
up to 30
Lighting Controls
30+
Residential Propane Backup Generators
12
Service Panel
60
Solar Panels
20 to 30
Solar System Batteries
3 to 12
Wind Turbine Generators
20
 
 
Floor and roof trusses and laminated strand lumber are durable household components, and engineered trim may last 30 years.
 
ENGINEERED LUMBER
YEARS
Engineered Joists
80+
Laminated Strand Lumber
100+
Laminated Veneer Lumber
80+
Trusses
100+
  

 

 

Fastener manufacturers do not give lifespans for their products because they vary too much based on where the fasteners are installed in a home, the materials in which they're installed, and the local climate and environment.  However, inspectors can use the guidelines below to make educated judgments about the materials they inspect.
 
FASTENERS, CONNECTORS & STEEL
YEARS
Adjustable Steel Columns
50+
Fasteners (bright)
25 to 60
Fasteners (copper)
65 to 80+
Fasteners (galvanized)
10+
Fasteners (electro-galvanized)
15 to 45
Fasteners (hot-dipped galvanized)
35 to 60
Fasteners (stainless)
65 to 100+
Steel Beams
200+
Steel Columns 100+
Steel Plates
100+
 
 
Flooring life is dependent on maintenance and the amount of foot traffic the floor endures.
 
 
FLOORING
YEARS
All Wood Floors
100+
Bamboo
100+
Brick Pavers
100+
Carpet
8 to 10
Concrete
50+
Engineered Wood
50+
Exotic Wood
100+
Granite
100+
Laminate
15 to 25
Linoleum
25
Marble
100+
Other Domestic Wood
100+
Slate
100
Terrazzo
75+
Tile
75 to 100
Vinyl
25
 
 
Concrete and poured-block footings and foundations will last a lifetime, assuming they were properly built.  Waterproofing with bituminous coating lasts 10 years, but if it cracks, it is immediately damaged.
 
FOUNDATIONS
YEARS
Baseboard Waterproofing System
50
Bituminous-Coating Waterproofing
10
Concrete Block
100+
Insulated Concrete Forms (ICFs)
100
Post and Pier
20 to 65
Post and Tensioned Slab on Grade
100+
Poured-Concrete Footings and Foundation
100+
Slab on Grade (concrete)
100
Wood Foundation
5 to 40
Permanent Wood Foundation (PWF; treated)
75
 
 
Framing and structural systems have extended longevities; poured-concrete systems, timber frame houses and structural insulated panels will all last a lifetime. 
 
FRAMING
YEARS
Log
80 to 200
Poured-Concrete Systems
100+
Steel
100+
Structural Insulated Panels (SIPs)
100+
Timber Frame
100+
 
 
The quality and frequency of use will affect the longevity of garage doors and openers.
 
GARAGES
YEARS
Garage Doors
20 to 25
Garage Door Openers   
10 to 15
 
 
Home technology systems have diverse life expectancies and may have to be upgraded due to evolution in technology.
 
HOME TECHNOLOGY
YEARS
Built-In Audio
20
Carbon Monoxide Detectors* 5
Door Bells
45
Home Automation System
5 to 50
Intercoms
20
Security System
5 to 20
Smoke/Heat Detectors*
less than 10 
Wireless Home Networks
5+
* Batteries should be changed at least annually.
 
 
Thermostats may last 35 years but they are usually replaced before they fail due to technological improvements.
 
HVAC
YEARS
Air Conditioner (central)
7 to 15
Air Exchanger
15
Attic Fan
15 to 25
Boiler
40
Burner
10+
Ceiling Fan
5 to 10
Condenser
8 to 20
Dampers
20+
Dehumidifier
8
Diffusers, Grilles and Registers
25
Ducting
60 to 100
Electric Radiant Heater
40
Evaporator Cooler
15 to 25
Furnace
15 to 25
Gas Fireplace
15 to 25
Heat Exchanger
10 to 15
Heat Pump
10 to 15
Heat-Recovery Ventilator
20
Hot-Water and Steam-Radiant Boiler
40
Humidifier
12
Induction and Fan-Coil Units
10 to 15
Chimney Cap (concrete)
100+
Chimney Cap (metal)
10 to 20
Chimney Cap (mortar)
15
Chimney Flue Tile
40 to 120
Thermostats
35
Ventilator 7
 
 
As long as they are not punctured, cut or burned and are kept dry and away from UV rays, cellulose, fiberglass and foam insulation materials will last a lifetime. This is true regardless of whether they were installed as loose-fill, housewrap or batts/rolls.
 
INSULATION & INFILTRATION BARRIERS
YEARS
Batts/Rolls
100+
Black Paper (felt paper)
15 to 30
Cellulose
100+
Fiberglass
100+
Foamboard
100+
Housewrap
80+
Liquid-Applied Membrane
50
Loose-Fill
100+
Rock Wool
100+
Wrap Tape
80+
 
  
Masonry is one of the most enduring household components. Fireplaces, chimneys and brick veneers can last the lifetime of a home.
 
MASONRY & CONCRETE   
YEARS
Brick
100+
Insulated Concrete Forms (hybrid block)
100+
Concrete Masonry Units (CMUs)
100+
Man-Made Stone
25
Masonry Sealant
2 to 20
Stone
100+
Stucco/EIFS
50+
Veneer
100+
 
 
Custom millwork and stair parts will last a lifetime and are typically only upgraded for aesthetic reasons.
 
MOLDING, MILLWORK & TRIM
YEARS
Attic Stairs (pull-down) 
50
Custom Millwork
100+
Pre-Built Stairs
100+
Stair Parts
100+
Stairs
100+
 
 
 
The lifetime of any wood product depends heavily on moisture intrusion.
 
PANELS
YEARS
Flooring Underlayment 
25
Hardboard
40
Particleboard
60
Plywood
100
Softwood
30
Oriented Strand Board (OSB)
60 
Wall Panels
100+
 
 
The quality of plumbing fixtures varies dramatically.  The mineral content of water can shorten the life expectancy of water heaters and clog showerheads.  Also, some finishes may require special maintenance with approved cleaning agents per the manufacturers in order to last their expected service lives.
 
PLUMBING, FIXTURES & FAUCETS
YEARS
ABS and PVC Waste Pipe
50 to 80
Accessible/ADA Handles
100+
Acrylic Kitchen Sink
50
Cast-Iron Bathtub
100
Cast-Iron Waste Pipe (above ground)
60
Cast-Iron Waste Pipe (below ground)
50 to 60
Concrete Waste Pipe
100+
Copper Water Lines
70
Enameled Steel Kitchen Sink
5 to 10+
Faucets and Spray Hose
15 to 20
Fiberglass Bathtub and Shower
20
Gas Lines (black steel)
75
Gas Lines (flex)
30
Hose Bibs
20 to 30
Instant (on-demand) Water Heater
10
PEX 40
Plastic Water Lines
75
Saunas/Steam Room
15 to 20
Sewer Grinder Pump
10
Shower Enclosure/Module
50
Shower Doors
20
Showerheads
100+ (if not clogged by mineral/other deposits)
Soapstone Kitchen Sink
100+
Sump Pump
7
Toilet Tank Components
5
Toilets, Bidets and Urinals
100+
Vent Fan (ceiling)
5 to 10
Vessel Sink (stone, glass, porcelain, copper)
5 to 20+
Water Heater (conventional)
6 to 12
Water Line (copper)
50
Water Line (plastic)
50
Well Pump
15
Water Softener
20
Whirlpool Tub
20 to 50
 
 
 
Radon systems have but one moving part:  the radon fan.
 
RADON SYSTEMS
YEARS
Air Exchanger
15
Barometric Backdraft Damper/Fresh-Air Intake
20
Caulking
5 to 10
Labeling
25
Manometer
15
Piping
50+
Radon Fan
5 to 8
 
 
The life of a roof depends on local weather conditions, building and design, material quality, and adequate maintenance.  Hot climates drastically reduce asphalt shingle life.  Roofs in areas that experience severe weather, such as hail, tornadoes and/or hurricanes may also experience a shorter-than-normal lifespan overall or may incur isolated damage that requires repair in order to ensure the service life of the surrounding roofing materials.
 
ROOFING
YEARS
Aluminum Coating
3 to 7
Asphalt Shingles (3-tab)
20
Asphalt (architectural)
30
BUR (built-up roofing)
30
Clay/Concrete
100+
Coal and Tar
30
Copper
70+
EPDM (ethylene propylene diene monomer) Rubber
15 to 25
Fiber Cement
25
Green (vegetation-covered)
5 to 40
Metal
40 to 80
Modified Bitumen
20
Simulated Slate
10 to 35
Slate
60 to 150
TPO
7 to 20
Wood
25
 
 
Outside siding materials typically last a lifetime.  Some exterior components may require protection through appropriate paints or sealants, as well as regular maintenance.  Also, while well-maintained and undamaged flashing can last a long time, it is their connections that tend to fail, so seasonal inspection and maintenance are strongly recommended.
 
SIDINGS, FLASHING & ACCESSORIES
YEARS
Aluminum Siding
25 to 40+
Aluminum Gutters, Downspouts, Soffit and Fascia
20 to 40+
Asbestos Shingle
100
Brick
100+
Cementitious
100+
Copper Downspouts
100
Copper Gutters
50+
Engineered Wood
100+
Fiber Cement
100+
Galvanized Steel Gutters/Downspouts
20
Manufactured Stone
100+
Stone
100+
Stucco/EIFS
50+
Trim
25
Vinyl Siding 60
Vinyl Gutters and Downspouts
25+
Wood/Exterior Shutters 20
 
 
Site and landscaping elements have life expectancies that vary dramatically. 
 
SITE & LANDSCAPING
YEARS
American Red Clay
100+
Asphalt Driveway
15 to 20
Brick and Concrete Patio
15 to 25
Clay Paving
100+
Concrete Walks
40 to 50
Controllers
15
Gravel Walks
4 to 6
Mulch
1 to 2
Polyvinyl Fencing 100+
Sprinkler Heads 10 to 14
Underground PVC Piping 60+
Valves
20
Wood Chips
1 to 5
Wood Fencing
20
 
 
Swimming pools are composed of many systems and components, all with varying life expectancies.
 
SWIMMING POOLS
YEARS
Concrete Shell
25+
Cover
7
Diving Board
10
Filter and Pump
10
Interior Finish
10 to 35
Vinyl Liner
10
Pool Water Heater
8
Waterline Tile
15+
 
 
Aluminum windows are expected to last between 15 and 20 years, while wooden windows should last nearly 30 years.
 
WINDOWS
YEARS
Aluminum/Aluminum-Clad
15 to 20
Double-Pane
8 to 20
Skylights
10 to 20
Window Glazing 10+
Vinyl/Fiberglass Windows
20 to 40
Wood
30+

Note: Life expectancy varies with usage, weather, installation, maintenance and quality of materials.  This list should be used only as a general guideline and not as a guarantee or warranty regarding the performance or life expectancy of any appliance, product, system or component.