Many homeowners rely on both a private well for water supply and a septic system for wastewater treatment. To ensure a clean and healthy water supply both systems need to function properly. The most likely source of contamination to a drinking water well is a nearby septic system failure, and typically, the nearest septic system is your own. If your home has a septic system of any type you are responsible for maintaining it. There are many different types of septic system designs. The most common type used for single family homes is a traditional septic system that consists of a single chamber septic tank and drain/leach field. The tank receives the toilet and drain waste water from the house and allows the solids to settle down to the bottom of the tank where the anaerobic bacteria that live in the tank digest the organic materials while the effluent (water around all that stuff) flows out to the leach field to be purified by passing through soil until it reaches the groundwater. Scum consisting of oil and grease floats on top of the water layer and can be pulled into the leach field limiting its effectiveness. The septic tank effluent water is either pumped or allowed to flow to a leach field where it percolates into the soil, which provides final treatment by removing harmful bacteria, viruses, and nutrients.
Suitable soil is necessary for successful wastewater treatment. The “percolation rate” is the rate at which water moves through soil. The acceptable rates are between one minute and one hour per inch of soil. Take either more or less time for the water to pass through your soil and the natural soil is unsuitable for treatment of the waste water. If the water moves too slowly through the soil the leach field will flood with contaminated, foul smelling water or the water will back up into the house. If the water moves too quickly thought the soil the water will not be adequately treated and contaminate nearby ground or surface water. Other types of septic systems are grouped together and called alternative on-site sewage systems, AOSS. One example of an AOSS is an aerobic system consists of a multi chamber tank or several tanks. After separation of solids in the first tank waste is forced through a filter into a second chamber or tank where air is pumped in to enhance aerobic bacteria which decomposes the organic material. The waste then flows into a third chamber or settling chamber which collects the bacteria and passes the liquid on to the leach field or drip field. Aerobic systems can remove more than 90% of the organic material and suspended solids within the tanks themselves, but require much more maintenance. Other type of AOSS include traditional septic tanks followed by treatment with tanks filled with peat, or sand mounds, or other soil absorption system that provide the secondary treatment.
In Virginia all AOSS are required to have a licensed operator maintain the system and be inspected at least annually. For more information on AOSS regulations and requirements see the Guidance Document from the Virginia Department of Health. Indoor water use in the typical single-family home is between 50-70 gallons per person per day. Septic systems are sized by bedrooms, which is an estimate of the number of people living in a home. However, even if the number of people living within your home is appropriate for the size of the septic system, you can still overload the system. Use too much water in a short period of time and the system will be overwhelmed. Each time the system is overwhelmed untreated sewage will leave the tank and begin to clog the leach field. If the amount of wastewater entering the system is chronically more than the system can handle, the wastewater containing raw sewage eventually backs up into the house or yard and creates a health hazard. By the time you can smell or see a problem, however, the damage to the leach field might already be done. Replacement of a leach field can run to the tens of thousands of dollars. So caring for your septic system not only cares for the earth but also cares for your wallet.
By limiting your water use and spreading out peak demands on the system you can reduce the amount of wastewater your system must treat. When you have your system inspected and pumped as needed, you reduce the chance of system failure. The US EPA’s Homeowner’s Guide to Septic Systems is a terrific basic guide to caring for and maintaining your septic system. Follow the Dos and Don’ts and your septic system may last for decades. Remember though, what goes into your septic system goes into the earth. Rethink the products you use to clean your house. Paint, solvents, gasoline, insecticides and poisons should never go down your drain. Every chemical you pour down your drain is buried in your yard. In a multitude of ways your yard is part of the earth’s yard. The functional lifetime of a traditional septic system is limited. The system is designed so that with proper maintenance it will last 20 to 30 years, under the best conditions. Many other factors can cause early failure of a septic system. Pipes blocked by roots, soils saturated by storm water, compacting of the drain field by parking vehicles or heavy objects on the top of the field, improper location, poor original design or poor installation can all lead to major problems. Septic systems and AOSS fail because they are abused, improperly maintained or just old. Remember that the entire functioning of a septic system is based on natural ecological cycles. It needs to be treated kindly and kept in balance. When a system is poorly maintained and not pumped out on a regular basis, sludge (solid material) builds up inside the septic tank, and then flows into the leach field, clogging it beyond repair. Excessive load from toilets, garbage disposal, putting grease, coffee grinds, kitty litter down the drain will shorten the life of and potentially overload the system.
Even with proper use and maintenance the system will wear out. Eventually, the soil around the leach field becomes clogged with organic material, forcing sewage upward into the yard or back into the house. Before that happens, however, there are warnings signs that you need to pay attention to.
Signs that a Septic System is Failing
1. Sewage backup in your drains or toilets. This is often seen as an unpleasant smelling black liquid.
2. Slow flushing of all or most of your toilets. Many of the drains in your house will drain much slower than usual, despite the use of plungers or drain cleaning products (which by the way should not be used with a septic system). Unfortunately, this is often gradual and goes unnoticed.
3. Liquid seeping along the surface of the ground in the back yard near the leach field. It may or may not have a noticeable odor associated with it. Lush green grass growing over the absorption field, even during dry weather or visual stripes in the grass texture and quality is often an indication that an excessive amount of liquid from your system is moving up through the soil, instead of downward, as it should. While some upward movement of liquid from the leach field is expected, too much could indicate major problems.
4. The presence of nitrates or bacteria in the drinking water well. This indicates that liquid from the system may be flowing into the well through the ground or over the surface. Annual water testing will indicate if you have this problem.
With alternative septic system assessing functionality is relatively simple for a qualified inspector (as required in Virginia). AOSS require maintenance to keep functioning properly and so AOSS regulations in Virginia require that these systems are installed with conservative horizontal set backs, are operated and maintained by a licensed operator, are sampled by a licensed operator every five years (with some older AOSS exempt from the sampling requirement), and an operating manual and records maintained on site. Remember that AOSS also need to have their primary tank pumped regularly and these expensive systems need to be treated with care.