Septic Systems: What You Need To Know When Building or Buying a House

Andrew Lake
NSFC Engineering Scientist

What should I know about onsite wastewater treatment and disposal systems when purchasing a home or buying property?

Editor’s Note: This column is based on calls received over the National Small Flows Clearinghouse (NSFC) technical assistance hotline. If you have further questions concerning purchasing an onsite treatment system, call (800) 624-8301 or (304) 293-4191 and ask to speak with a technical assistant.

Whether you are purchasing a home with an existing onsite wastewater treatment and disposal system (OSDS), or building your own home that will need an OSDS, there are a few things that you, the purchaser/builder, should be aware of to protect yourself and the environment.

Buying a Home

If there is an existing OSDS, it is important that you have the entire system inspected by a licensed inspector or the proper local permitting authority. Often, this procedure is termed a Property Transfer Inspection (PTI). A PTI is necessary to determine whether the existing system is functioning properly and meeting current local/state regulatory requirements. The PTI protects you, the potential new owner of the OSDS, by relieving you of the financial responsibility of repairing or replacing a failing or substandard system. If there are problems with the OSDS, the PTI will make the current owner responsible for bringing the system up to code.

The system inspection consists of locating the OSDS and identifying the system components (i.e., septic tank, aerobic treatment unit [ATU], sand filters, and dispersal methods). The primary treatment unit (septic tank or ATU) will be checked for structural integrity, proper size for the residence, and liquid volume in the tank. If the septic tank contains effluent filters, these will also be inspected. The inspection process will be similar for an ATU; however, different components, such as the aerator and electrical devices, will need to be inspected.

The dispersal system, such as a drainfield or soil absorption system, will also need to be inspected. As mentioned earlier, the inspector needs to locate the dispersal system and determine the size of the dispersal area to ensure that it is adequate for the residence. Once it is located, the inspector will examine the site for signs of system failure. Some of these signs may include soggy ground over the drainfield; ponding/surfacing effluent; changes in grass color or thickness; and cover, such as trees, bushes, and shrubs located next to, or around, the system that can potentially clog or disrupt the distribution network. The inspector will also probe the soil in the drainfield or soil absorption area to determine if the soil is adequately handling the treated effluent being dispersed.

In some cases, PTIs are required. Some entities that may require a PTI to include state and/or local regulatory authorities, banking/lending institutions, and real estate agencies. For your own protection as a prospective buyer, you should insist on a complete inspection whether it is required or not. Contact the local regulatory authority or ask the lending institution you’re working with if they require an inspection.

Building A Home

If you are planning to build a home that will not be located on or near a centralized wastewater collection system, a site evaluation should be conducted prior to purchasing property. It will be up to you, the potential land purchaser, to have the land evaluated to be certain the property can be “developed” (i.e., it is conducive to onsite wastewater treatment and dispersal).

There are some very important aspects of the property that a site evaluation should consider. The size of the lot is important for determining the ideal location of the wastewater treatment and dispersal system. The land area and location of the onsite system must meet the required horizontal separation distances (the regulated distance from adjacent properties, drinking water wells if there are no public water services available, or surface water bodies). In addition to the size of the property, another and quite possibly more important component that needs to be evaluated is the soil.

Soil characteristics play a major role in siting an onsite wastewater system. It is important to know the site conditions before purchasing the land. If site conditions are unacceptable for an OSDS, chances are you will be stuck with property that you cannot build upon.

For example, imagine that you purchased a parcel of land with a great view or that seems ideal for your particular needs, but the soil conditions don’t meet specified requirements for wastewater dispersal. The physical site characteristics must be evaluated to ensure that the soil can handle the amount and quality of effluent being discharged. These characteristics include soil classification or percolation tests; vertical separation (subsurface) distances to restrictive horizons, such as bedrock; the natural groundwater table; and the seasonal high water table. If these conditions are not acceptable and do not meet the requirements established by your local or state regulatory authority, you will want to know this prior to making any commitment to purchasing the property.

If any of these site characteristics cannot be met, all may not be lost. There are alternative methods for onsite wastewater treatment and disposal. It is vital, however, to work closely with local regulatory authorities because they will be able to provide you with options that would be approved for your site’s conditions.

Again, it is the purchaser’s responsibility to schedule a site evaluation. Your local health department or state regulatory agency should be able to provide you with contacts for a licensed inspector or soil evaluator. If the site meets the requirements and can be developed, it is also important to contact a reputable OSDS installer or designer. You may also check the local yellow pages or ask questions of others living in the area to help determine who would be most appropriate to perform your site evaluation and/or design and install your OSDS. The designer or installer, in cooperation with the local health department or permitting authority, can help you determine which wastewater treatment and dispersal technology will be appropriate for your site.

Once you become the proud new owner of an onsite wastewater treatment and dispersal system, you need to take care of your new investment. Knowing the location of the system and understanding how the system and its components work are very important to you as the new homeowner. Proper maintenance and care of your onsite system will ensure that your wastewater is properly treated and safely returned to the environment. It is also important for you, the purchaser, to be present when all of these inspections are conducted. This will provide you the opportunity to ask questions and have a full understanding of your wastewater treatment and dispersal system.

The NSFC has products and publications that can assist you in all phases of these inspections, site evaluations, and in choosing an appropriate onsite wastewater treatment and dispersal system. Please feel free to contact the NSFC at (800) 624-8301 for more information.

Products

Pipeline

A Homeowner’s Guide to Onsite System Regulations (Item #SFPLNL12) The Winter 1998, Volume 9, Number 1 issue of Pipeline examines some common onsite wastewater system regulations as they affect property transfers, professional qualifications, operation and maintenance, system changes and repairs, and the steps for system approval. The price of this eight-page NSFC newsletter is 20 cents.

Inspections Equal Preventative Care for Onsite Systems (Item #SFPLNL13) The Spring 1998, Volume 9, Number 2 issue of Pipeline focuses on the advantages of having onsite wastewater systems regularly inspected, including discussions about when the onsite system should be inspected, who should inspect it, the homeowner’s role in the process, and what happens during an inspection. The price of this eight-page NSFC newsletter is 20 cents.

Site Evaluations (Item #SFPLNL21) The Spring 2000, Volume 11, Number 2 issue of Pipeline explains the importance of a site evaluation prior to installing an onsite wastewater system, and how the testing determines the type of onsite system that is appropriate for a particular site. Planning for an onsite system, including the preliminary site evaluation, soil surveys, field testing, landscape contour and subsurface drainage, soil tests, texture, structure, and other soil properties, as well as water movement, are all discussed. Suggested site evaluation procedures and tips are offered. This current issue of the eight-page NSFC newsletter is free of charge.

Poster

Onsite Wastewater Treatment for Small Communities and Rural Areas (Item #WWPSPE02) Developed by the NSFC, this updated poster provides descriptions and illustrations of various onsite conventional and alternative wastewater treatment and disposal technologies. These technologies are applicable to individual homes, schools, restaurants, and other small-flow situations. There is also a section about systems that can be installed in difficult site conditions. The cost for this poster is $1.25.

Booklet

State Level Onsite Wastewater Regulatory Contacts (Item #WWBLRG34) Compiled by the NSFC, this list includes regulatory contacts for states that have onsite wastewater regulations. A contact person’s name, department, address, and telephone number is provided. This eight-page booklet is offered free of charge.