Onlot Sewage Program (Home Buyer's / Builders Guide)

Many Pennsylvanians, particularly those living in rural areas, depend on onlot systems (also called "septic" systems) to treat the sewage from their home. Properly functioning onlot systems treat, distribute and dispose of sewage through a clean, economic and efficient process.

The Pennsylvania Sewage Facilities Act (Act 537 of 1966, as amended) requires local agencies (local municipalities, group of municipalities or County Health Department) to administer a permitting program for the installation of onlot sewage disposal systems. The purpose of this permitting program is to ensure uniform standards of system design and installation and thus prevent outbreaks of environmental and public health problems from substandard or malfunctioning onlot systems.

Investigate Before You Invest

Planning to buy a lot that needs to have an onlot sewage disposal system installed? Be sure to investigate before you buy. Among other precautions, find out if:

If you have any questions or doubts about the required permits or subdivision approvals for the lot you are considering, contact the local government officials where the lot is located. Be sure to contact the SEO.

Remember, what may look like the dream lot could lead to nightmares and, possibly, financial ruin. So, investigate before you invest!

Working With Your Local SEO

The onlot permit program is administered by a local agency. This organization may be a municipality, a multi-municipal organization, or a county or joint county Department of Health. An SEO is the local agency employee responsible for reviewing and approving permit applications and being knowledgeable about onlot systems. While the SEO is trained by DEP and certified by the State Board for Certification of Sewage Enforcement Officers, the SEO is actually an employee of the local agency, not DEP. To find out how to contact the local agency SEO, start with your local municipal office.

Getting Your Permit

To obtain a permit for an onlot sewage system, these steps must be followed in the order listed:

  1. The lot owner, or an agent for the owner, applies for a permit through the SEO. If the lot is in a subdivision, the lot owner should first ensure that all other state, county and local planning, zoning and land use requirements have been met by checking with municipal officials.
  2. The SEO measures slope and conducts soil profile examinations and percolation tests to determine if the site is suitable for an onlot system. If suitable, the SEO determines which type of onlot system will work best. (The types of systems are listed later in this document).
  3.  If the site is suitable, the SEO informs the lot owner or agent to proceed with the system design. The system must be designed with certain factors in mind, including site conditions, isolation distances, percolation test results and the number of bedrooms in the home. (The SEO is specifically prohibited from designing the system.)
  4. Once the lot owner or agent has the design and plot plan, they are submitted as part of the permit application to the SEO. The SEO must approve or deny the permit within seven days of receiving a complete application. If approved, the SEO issues the permit and the applicant may begin installing the system and building the home. If denied, the SEO notifies the applicant and provides the opportunity to an appeal hearing before the local agency.
  5. The SEO may oversee any step of the installation, but must inspect the completed system before it is covered.

Knowing the Types of Onlot Systems

There are five basic conventional onlot systems permitted for use on residential lots. They are:

The type of system selected and permitted depends on the site conditions and the type of soil on the lot.

Choosing an Alternate System

In some cases, when a lot does not qualify for a conventional onlot disposal system, the lot owner may wish to consider an alternate system. There are a variety of alternate onlot system types DEP has approved over the years that may be appropriate. This list is updated periodically and is available online at DEP's website (, PA Keyword "Wastewater." Keep in mind, however, some lots just are not suitable for any type of disposal system due to inadequate soils, high water table, steep slopes, or other important factors.

Some alternate systems include:

There are specific requirements that must be met when using an alternate system. Contact your SEO or DEP for information about these requirements.

DEP also has guidelines for the development and use of experimental systems. Successful experimental systems eventually may be accepted as alternate systems, making them available for use at other difficult sites.

Observing the Installation

When you have the permit (which is valid for three years), you are ready for the installation of your system. Be sure to hire a reputable contractor because the best designed system can malfunction if not properly installed. Get written bids from potential contractors, ask for a list of references, and ask professional associations or your local SEO if they know these contractors. You, too, should be somewhat aware of the proper installation procedures and observe the contractor's activities. Ask your local SEO for information about proper installation procedures.

Continuing Operation and Maintenance

Once the onlot system is installed, the homeowner becomes responsible for following proper operating and maintenance procedures to prevent malfunctions and ensure long-term use of the system. See DEP's "Onlot System Operators and Maintenance (Homeowner's Guide)" available on the DEP website for additional information.

Understanding DEP's Role

DEP's primary role in the onlot permit program is to provide financial assistance and oversight to local agencies, train SEOs and help local agencies carry out their permitting and enforcement responsibilities.