• What Are Septic Systems?
  
• How do Septic Systems Work?
  
• What are the Components of a Private Septic System?
  
• Where are These Components Located?
  
• Care and Maintenance
  
• Why do Septic Systems Fail?
• How Long Should a Septic System Last?
  
• What are the Signs of a Failing System?
  
• If I Plan on Repairing, Installing, or Replacing A System, What should I expect?
  
• If my Family is Growing and I add a New Bedroom, What Should I Expect?
  
• How Big Should a Septic Tank Be?
  
• How Big Should the Leach Field Be?
  
• What is Gray Water?
  
• Alternative Systems
  
  

What are Septic Systems?

Septic systems are considered to be on-site systems designed to safely dispose of biological sanitary waste. "Gray water", such as laundry waste, is part of the waste system, but it may not result in what is referred to as "biological" waste.

How do Septic Systems Work?

Basically a septic system provides a "holding tank" where natural bacterial action decomposes human waste products into environmentally acceptable components - the major end-components being water, mixed with some other components that are not readily consumed by the bacterial action, gases, and undigested solids. The end products, except the undigested solids, are then discharged to the on-site environment.

What are the Components of a Private Septic System?

The things that are most obvious are the things seen every day - the sinks, toilets, and pipes in a normal house. What is not visible is the underground septic system and the ground itself, both which greatly impact the systems performance. The individual parts of the system are the septic tank, a distribution box, and a leach field. Bacterial action takes place in the septic tank where the end products are mainly water, gases, and undigested material, called sludge that sinks to the bottom of the tank and scum that floats to the top of the tank. The septic tank contains baffles that prevent any scum that floats to the surface and sludge that settles to the bottom from passing out of the tank. The gases that are generated vent to the atmosphere via the plumbing vent system. From the septic tank, the segregated and relatively clear liquid flows into a small distribution box where it is then metered out to several perforated pipes. These perforated pipes then deliver the liquid to a large soil surface area, called a leach field, or absorption field, for absorption. The soil also acts as a filter to remove any small amounts of solids that may be carried along with the liquid. The sludge in the bottom of the tank must be periodically pumped out and disposed properly.

Where are These Components Located?

The concrete, or sometimes steel, septic tank is buried in the ground, usually a minimum of 10 feet from the house. The top of the tank is usually about one foot below the soil surface so it can be periodically opened for inspection and pumping. If you do not know for sure where the tank is located, the first step is to locate where the house sewer pipe leaves the house. In a house with a basement, this is where the pipe passes through the wall. Locating the exit point may be more difficult for a house with no basement. If the pipe exit can be found, the tank normally begins about 10 feet from the house outside wall and in line with the house sewer pipe. If the soil is not frozen, you can usually find the tank by pushing a slender metal rod into the ground until it hits the buried tank. You can buy a metal rod about 1/8 inch in diameter for a few dollars at most hardware stores. Be careful when probing for the tank and avoid hammering the metal rod into the ground - you could break a sewer pipe. The distribution box is much smaller than the septic tank and is usual found about 20 feet from the house. It too is usually only about one foot below the ground. Again, you can probe the soil carefully to locate the distribution box with a slender metal rod.

From the distribution box, several pipes direct liquid to a series of pipes in trenches called laterals. The pipes in the trenches have holes in them to allow the liquid to be evenly distributed within the trench. To keep the pipes from being blocked with soil and to provide a space for water to be stored while it is being absorbed by the soil, the pipes are laid in a bed of crushed stone. Above the stone is a soil filter (usually one or two layers of what is called untreated building paper). Above the soil filter is top soil in which grass is planted.

Equally important is where the components should not be. If there are wells, either yours or a neighbor's, the leach field must be a minimum of 100 feet from the location of the well. In some areas, the well is not allowed to be down-slope from the leach field. If there is a stream or pond, the leach field must also be a minimum of 100 feet from the mean high water mark. Normally, no part of the system should be within 10 feet of a property line. In some areas and in unusual conditions, minimum distances may be greater than those noted here. In addition, no part of the system should be under a porch or driveway and you should not drive heavy vehicles (including automobiles) over the system lest the system be damaged.

Care and Maintenance

Conventional septic systems are not entirely care free. The undigested solids (sludge) in the bottom of the septic tank should be pumped out every two to four years, depending on usage and tank size. If the sludge is not removed periodically, it will eventually carry over into the leach field and cause the field to fail. A well designed system can handle a reasonable amount of normal household chemicals such as drain cleaners, laundry detergent and bleach, however excessive usage can be detrimental. You should avoid putting in chemicals that are toxic to the bacteria, such as paint thinner, solvents, insecticides, etc. Cooking fats and grease should also be avoided. If a garbage disposal is used, more frequent tank pumping may be needed.

Why Septic Systems Fail

If the liquid effluent cannot soak into the soil surrounding the leach field, sewage may back up into the system and overflow into the house or puddle on the surface of the ground. There are several possible causes for this problem.

Poor Soil Conditions, Faulty Design or Installation: A leaching system placed in unsuitable soil, a system that is too small for the house it serves, or an improperly constructed system may lead to early failure.

Soil Clogging: If sludge or scum is allowed to escape into the distribution box and from there into the leach field, the soil will quickly become clogged. If this happens, the liquid will no longer soak, or percolate, into the soil. This condition can be caused by broken baffles in the septic tank that allow sludge or scum to escape. Failure to have the tank pumped can also lead to a situation where the sludge and scum overwhelm the baffles.

High Water Table: During wet (or abnormally wet) seasons, groundwater may rise into the leach field and force sewage upward to the ground surface. This condition may mean the system has to be re-installed at a higher level. It may also be possible to intercept the high groundwater with a series of drains around the system called "curtain drains".

Roots: The roots of trees and bushes planted too close to the system can sometimes enter and block the pipes of the system. Removal of the plants and clearing the pipes of the roots is usually required.

Physical Damage: Trucks or heavy equipment passing over the system can damage pipes and joints to the point of rendering the system inoperable. You should be aware of the location of the system and direct traffic to avoid such damage.

How Long Should a Septic System Last?

You can expect a conventional septic system, such as that being described here, to last about 30 years. Some systems last much longer and some systems can fail earlier for reasons like those noted above. Other things can also affect the life of a septic system. For example, a system may have been providing satisfactory service for a previous owner for many years, only to fail shortly after you have bought the house. If the previous owners were a working couple with no children, the system was probably not heavily used; if yours is a family of six, the added load could push a marginal system over the edge and into failure.

What are the Signs of a Failing System?

Sewage backup into the home is one possible sign of a failing system. However, backup can also be caused by a blockage somewhere between the house and the septic tank (this is relatively easy to fix). Another possible sign of failure is a smell of sewage outside the house. If this smell is more noticeable after a lot of water has been put into the system - multiple showers or several loads of laundry (if the laundry waste discharges into the septic system), for example - this may be an indication that the leach field is failing. The smell may also be accompanied by a "spongy" feeling in some areas of the leach field, near the distribution box, or near the septic tank. The "spongy" feel may be caused by water and waste being pushed to or near ground level. If ponding water is also seen, this is called "breakthrough" and is an almost positive indication of failure of one or more parts of the system. This smell, however, can also originate at the plumbing vent. In either case, further investigation is warranted. If you see such signs, a dye test may confirm your suspicions. For this test, a special strong dye is put in the system - usually by flushing it down the toilet. A significant amount of water is then washed into the system. If there is "breakthrough", the dye will become visible on the ground surface. If the dye is seen on the surface, this would be a very strong indication that the system has failed. A home inspector, a licensed professional engineer, or a septic system contractor can usually perform this test for you.

If I Plan on Repairing, Installing, or Replacing A System, What should I expect?

There are two major factors involved in adding a new system or repairing or replacing an existing one. The first is the cost; the second is the inconvenience of possibly not being able to use the existing system while a replacement is being installed. For new construction, the second factor is not usually a major consideration. Repair or replacement cost will obviously depend on what has to be repaired and/or replaced. Englewood Environmental will gladly provide you with a quote for your unique situation. Please click here to request a quote.

If my Family is Growing and I add a New Bedroom, What Should I Expect?

Septic systems are designed to dispose of household biological waste. The amount of waste to be handled depends on a number of factors. Among these are the number of people living in the house and their lifestyle. After many years of experience, a major guideline in determining the size and capability of a septic system has been correlated to the number of bedrooms in a house. The number of bedrooms typically determines the number of people generating waste and hence the amount of waste that must be handled. If your family is growing and a new bedroom is needed, then the load on the septic system is also increased. If the septic system capability does not keep up with the increased demand, system failure may occur.

How Big Should a Septic Tank Be?

Septic tanks are sized according to the amount of liquid waste they must process. This is typically done by counting the number of bedrooms.

How Big Should the Leach Field Be?

Determining the required size of a leach field is a bit more complicated. The first thing to consider is the nature of the soil in which the leach field is to be constructed. Because water has to be absorbed in the soil, we need to know how fast it can be absorbed. This is called the percolation rate and is expressed as the time it takes for water in a test hole to decrease in level by one inch (minutes/inch). We must also know the type of soil and whether seasonal changes in the natural level of groundwater will interfere with the satisfactory operation of the system. Seasonal groundwater must be more than four feet from the bottom of the leach field trenches. Judgments regarding the soil conditions and percolation rates are best left to a professional. If the soil percolates very fast (less than one minute per inch) or very slow (greater than 60 minutes per inch) it will not be possible to install a standard leach field in the existing soil.

What is Gray Water?

Gray water is usually water from a laundry system, perhaps the effluent from a sump pump, the foundation footing drains, roof runoff, and sometimes shower drains. This water usually does not contain human waste products and does not need to be digested like human waste. The disposal requirements for this type of water are less stringent than those for human waste. If there is a space problem on your site, it may be possible to segregate the gray waste from the human waste and minimize the size of the system needed for control of the human waste.

Alternative Systems

The system discussed above is a conventional system installed in the soil that exists on the site. Where the site conditions do not lend themselves to installing this type of system, there are alternatives. For example, if ground water or percolation rates are unsuitable, it may be possible to install what is called a "mound" system. In a mound system, a suitable soil is placed above the unsuitable soil. A conventional system is then installed in the mound. There are some additional requirements for this type of design.

If there is not enough room for a conventional leach field, it may be possible to install one or more cesspools, or seepage pits. These units are usually round, require less open ground, and are deeper than a conventional leach field. Again, there are specific requirements for these systems.

Conventional, mound, and seepage pit systems all work by what is called anerobic bacterial action. This means the bacteria work without oxygen. Some systems are designed to be aerobic - meaning the bacteria need oxygen (air); There are also hybrid systems that use a combination of anerobic and aerobic sections.