CCGG provided advice for buyers of a house with a private water supply and we are doing the same for a house with a septic system.

A septic system, like water, is usually out of sight and out of mind. It consists of a treatment tank, which is buried in the yard, and an absorption area. The absorption area may be completely underground and unnoticeable or it may appear as an elevated mound. There are other types of systems but these are the most common.

Diagram of a Septic System

If you know nothing about on-lot disposal you’re probably in the majority. When buying a house, do not assume the system works properly because there are ways the seller can hide the symptoms of a faulty system.

This is something you must be aware of, and there is help available. Have the system checked by a professional. Click the link for a PDF document from Penn State regarding Septic System Inspections During Real Estate Transactions.

If you buy a house with a faulty system, you could pay $5,000-$20,000 or more to repair or replace it. The cost of the inspection before buying can be negotiated with the seller and/or you could put a contingency in your offer. If you really get stuck, there is a state program that can provide low-cost financing for repair or replacement of the septic system, but you do need to meet the requirements. The Pennsylvania Infrastructure Investment Authority funds this loan program.


What Is It?

Very simply put, all your wastewater goes into a treatment tank. The solids (sludge) settle to the bottom, and the floaters (scum) stay on top with water in between the layers. Bacteria go to work eating this material, reducing its volume. But bacteria can do only so much and, as new sewerage is continually added, the result is an accumulation of sludge and scum.

The water layer goes out the other end of the treatment tank to the absorption area where it percolates back into the ground. There is a baffle to keep the floaters in the treatment tank. If you have an elevated mound, the water probably goes to a dosing chamber where the water is pumped up into the mound. Of course this water is loaded with bacteria and some solids making it imperative to contain it.

The treatment tank and absorption area is sized for the house based on the number of bedrooms. If these systems properly installed, they will be functional forever, as long as the house remains empty. Most failures are caused by improper use and a neglect of maintenance.

What you do and don’t do will determine how long your system functions. Please refer to the Fact Sheets below for detailed information.

The Dos:
* Pump out the treatment tank on a regular basis. The time interval will depend on the number of people living in the house and how many “Don’ts” you do. Start with a 2-3 year interval for three residents and ask the person doing the pumping how much sludge and scum there is. You can then adjust the time between pump outs accordingly.

The Don’ts:
* Don’t use more water than necessary. For every drop that goes into the treatment tank, a drop goes to your absorption field. This water always has some solid matter in it and this is what causes the absorption field to clog. The absorption field was built to handle a certain amount of water per day. Extra water will cause hydraulic overload and solids from the treatment tank reduces the capacity.

* When a large volume of water enters the treatment tank, as from a bathtub or washer, it can cause a wave that stirs up the scum, dredge and water and sends even more solids out.

* Don’t put anything down the drain that can be disposed of in some other place. You’ll have to use your common sense here. The list includes the following common items: thick toilet paper, facial tissues, paper towels, disposable diapers, feminine hygiene products, cigarette butts, kitty litter, motor oil, antifreeze, paint, solvents and thinners, lawn and garden chemicals, unused prescriptions and other drugs, cleaning products, food scraps (sorry, garbage disposals are out), cooking oils, fats, grease etc.

* Don’t use products that are supposed to add bacteria to the treatment tank. In normal operation, your tank has all the bacteria it needs.

Many people never pump their treatment tank and the result is that it fills up with sludge and scum, leaving little room for water. Wastewater will now travel quickly through the treatment tank without allowing the sludge and scum to separate, allowing large quantities of sludge and scum to be carried to the absorption field causing its inevitable failure. If you’re careful what you put down the drain and have the treatment tank pumped on a regular basis, your system should last many, many years.

One last point to remember is that a septic system recycles water. Your well supplies water to your house for your use. When it goes down the drain, it eventually winds up back in the aquifer or a stream for someone else to use. If everything is working right, the recycled water is as good as when you got it. This may sound gross but water recycling has been going on throughout the history of our planet. The water we have today is the same water the dinosaurs had.

If your septic system is failing, you may have many unhappy neighbors.


Top 10 Reasons Why On-Lot Sewage Systems Fail By Albert Jarrett, Professor of Agricultural Engineering, Penn State University

Inspection of Existing Septic Systems During Real Estate Transactions [PDF file]

Site Evaluation for On-Lot Sewage Systems  (PDF) Proper design and operation of an on-lot sewage system hinges on the ability of the soil to absorb and renovate the wastewater flowing from the treatment tank.

On-Lot Sewage Systems (PDF) Describe the parts and function of on-lot sewage systems and the regulatory system governing their use.

Elevated Sand Mounds for On-lot Wastewater Treatment  (PDF) Explains what an elevated sand mound is and how, on sites requiring sand mound absorption areas smaller than 2500 square feet, they should be constructed and maintained.

Septic Tank Pumping (PDF) As the tank volume fills with sludge and scum increases, wastewater is retained in the tank for less time and the solids removal process becomes less effective and more solids escape into the soil absorption area. If too much sludge accumulates, the wastewater’s solids will flow to the soil absorption field causing system failure. To prevent this, the tank must be pumped periodically.

Preventing On-lot Sewage System Malfunctions(PDF) Assuming your on-lot system was properly sited, designed and installed, malfunctioning of on-lot sewage systems occurs for one of four reasons: faulty installation, hydraulic overloading, biological overloading or lack of maintenance. This fact sheet discusses each type of malfunction and suggests potential remedies for each.

Biomats (PDF) A biomat is a black, slimy jelly-like, slowly permeable layer of partially decomposed organic waste containing microorganisms that seek to feed and grow in this anaerobic environment. Biomats are often found in an on-lot sewage disposal system on the bottom and sidewalls of the aggregate-soil interface of the absorption area’s trenches or beds. This can lead to absorption field failure.

Use of Dyes and Tracers to Confirm Septic System Failures (PDF) In many cases, the signs of a failing system are visible—seepage appears at the soil surface, often with a smell of septage. Sometimes detecting a leak or malfunctioning component requires more than a visual inspection. Commercially available dyes and tracers can be used to establish the flowpath of wastewater and confirm a suspected problem.

Water Conservation Opportunities for Individual Residences Serviced by On-Lot Wastewater Disposal Systems (PDF) Answers questions about
1. How is water used in a typical household?
2. What amounts of water are involved in our normal daily activities?
3. How much wastewater is produced by these activities
4. How practical is water conservation for our household? (PENNVEST) (PDF) Inform homeowners about how to obtain low-cost financing for the improvement, repair or replacement of their existing on-lot sewage disposal systems. This loan program is funded by the Pennsylvania Infrastructure Investment Authority (PENNVEST), administered by the Pennsylvania Housing Finance Agency (PHFA), and supported by the Department of Environmental Protection (DEP).

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