Glossary

Act 537: The Pennsylvania Sewage Facilities Act, enacted January 24, 1966. It requires every municipality to maintain a DEP-approved Official Sewage Facilities Plan and creates the local-agency structure that makes PA septic permitting unlike most states.

Alternate SEO: Every Act 537 local agency must employ both a primary and an alternate Sewage Enforcement Officer, so permitting coverage never lapses.

Baffle: A barrier inside the septic tank controlling flow between compartments and keeping solids from reaching the absorption area. A failed baffle often produces symptoms that look like field failure.

Chapter 71: 25 Pa. Code Chapter 71 — the administration and sewage facilities planning rules, including planning modules and exemptions.

Chapter 73: 25 Pa. Code Chapter 73 — the technical standards for onlot sewage treatment facilities. These are the design rules your SEO and installer must follow.

Effluent: The liquid leaving the septic tank after solids settle out. Its quality determines how much treatment the soil still has to perform.

Elevated Sand Mound: A system where the absorption area is built above natural grade in an engineered sand bed. Common across Pennsylvania where clay soils, shallow bedrock, or a seasonal high water table rule out a conventional in-ground field.

Joint Local Agency: Two or more municipalities working together as a single Act 537 local agency, often sharing one SEO. Common in rural Pennsylvania where individual townships are too small to staff the role alone.

Local Agency: The body that administers septic permitting under Act 537. It can be an individual municipality, a joint local agency, or a county health department — which is why the answer to who issues your permit varies across Pennsylvania.

Official Plan: A municipality's DEP-approved Act 537 sewage facilities plan, addressing existing and future sewage disposal needs. If a township's plan is out of date, it can slow new construction permits.

OLDS: On-Lot Disposal System — Pennsylvania's regulatory term for what most homeowners call a septic system.

PENNVEST: The Pennsylvania Infrastructure Investment Authority. Its Homeowner Sewage Program, run with PHFA and DEP, lends up to $25,000 at 1.75% fixed for up to 20 years with no household income limits.

Percolation Test: A test measuring how quickly water moves through soil, used alongside soil probes to determine what system a site can support.

PHFA: The Pennsylvania Housing Finance Agency, which administers PENNVEST septic lending through participating local lenders. Reach them at 1-855-827-3466.

Planning Module: The Act 537 process for updating a municipality's Official Plan before a subdivision or new land development proceeds. DEP review commonly runs 60 to 120 days, which matters for construction timelines.

Replacement Area: Space reserved on a lot for an entirely new absorption area if the original fails. Lot size and soil quality together determine whether a property has one.

Riser: An extension bringing a buried tank access lid to ground level. Costs $200 to $400 and typically pays for itself within two pump-outs.

SEO (Sewage Enforcement Officer): The certified official who evaluates soil, approves system designs, issues permits, and inspects installations for an Act 537 local agency. In Pennsylvania the SEO — not a county health department — is the person you actually deal with.

Setback: The minimum required distance between a septic component and a well, property line, water body, or structure.

Sewage Advisory Committee: A committee representing the regulated community that reviews rules and procedures and advises the DEP Secretary.

Site Evaluation: The soil and site assessment determining what system a property can support. In Pennsylvania the SEO conducts or reviews it, and nothing gets built before it happens.

Sludge and Scum: The solids that settle to the bottom (sludge) or float to the top (scum) inside a septic tank. When these layers reach the outlet, solids escape to the absorption area — which pumping on schedule prevents.