Plumbing in a home with a septic system: what to know and who to call

Updated November 10, 2026 · KeystoneProGuide editorial team

How does a septic system change the way you use your plumbing?

Everything that goes down a drain ends up in the tank. The EPA puts it plainly: whether you flush it, grind it in the garbage disposal or pour it down a sink, it ends up in your septic system, where living organisms digest and treat the waste.

What should never go down the drains?

The EPA's rule of thumb is to flush nothing but human waste and toilet paper. Its list of things never to flush includes cooking grease or oil, non-flushable wipes, feminine hygiene products, diapers, dental floss, cigarette butts, coffee grounds, cat litter, paper towels, pharmaceuticals and household chemicals such as paint, solvents and pesticides.

At the sink, it says:

avoid chemical drain openers and use boiling water or a drain snake instead
never pour cooking oil or grease down the drain
never pour oil-based paints, solvents or large amounts of toxic cleaners down the drain
limit or stop using a garbage disposal, which adds fats, grease and solids that can clog the drainfield

Why does water use matter so much?

Because every gallon has to pass through the tank and drainfield. The EPA says efficient water use improves how a septic system works and lowers the risk of malfunction. A typical single-family home can use as much as 70 gallons per person per day indoors, and a single leaky or running toilet can add as much as 200 gallons a day. It suggests high-efficiency toilets, faucet aerators and efficient showerheads, choosing the right load size on the washing machine, and spreading laundry through the week rather than doing it all in one day, which it says can flood the drainfield.

Two plumbing choices weigh on this. Fixing leaks comes first; the EPA's meter test, reading the meter before and after two hours of no use, will tell you whether a hidden leak is feeding the tank. And a water softener adds load: Penn State Extension says each regeneration uses about 50 gallons, which may or may not overload a septic drainfield.

How often should the system be serviced?

The EPA says the average household system should be inspected at least every three years by a septic service professional, and that tanks are typically pumped every three to five years. Systems with pumps, float switches or other mechanical parts generally need inspection once a year, and a service contract is important for them. How often to pump depends on household size, the wastewater produced, the solids in it and the size of the tank.

The EPA gives a measurable test: the tank should be pumped when the bottom of the scum layer is within six inches of the outlet, the top of the sludge layer is within 12 inches of it, or sludge and scum make up more than 25 percent of the liquid depth. Ask the service provider to record those levels, and keep the reports.

How do you protect the drainfield?

The EPA lists three rules: do not park or drive on it; plant trees far enough away that roots stay out of the system; and keep roof drains, sump pumps and other rainwater drainage away from it, since excess water slows or stops treatment. If a plumber is installing a sump pump or rerouting a downspout, tell them where the drainfield is.

What are the signs that a septic system is failing?

Penn State Extension says a failing system can back wastewater up into the home or let it collect in the yard, creating health hazards, and can pollute wells, ponds and streams nearby. It notes that a regulatory inspection treats a system as malfunctioning only when wastewater is visibly surfacing or has backed up into the house, which is why it recommends a fuller inspection when buying.

Who permits septic work in southeastern Pennsylvania?

The county health department, in the four suburban counties.

Bucks: the Bucks County Health Department permits new and repaired systems, helps owners investigate and repair a malfunctioning system, and licenses pumping trucks; 215-345-3318. Its page points to low-cost state financing through PENNVEST for repairs, replacements or a first connection to public sewer.
Chester: the Chester County Health Department permits on-lot sewage systems and wells; 610-344-6225.
Delaware: the Delaware County Health Department handles Act 537 permits and enforcement and licenses liquid waste haulers; (484) 276-2100.
Montgomery: the Office of Public Health issues on-lot sewage permits through its local offices in Norristown, Pottstown and Willow Grove.

Penn State says a Sewage Enforcement Officer administers the state's on-lot rules, mainly permitting and overseeing new systems, and that some municipalities require inspections or pumping every 3 to 5 years.

Buying a house with a septic system?

Get it inspected separately. Penn State Extension says a real estate septic inspection must be done by a trained, certified inspector, is more detailed than a typical home inspection, and requires the tanks to be pumped. It puts the total for south-central Pennsylvania in 2026 at about $625 to $1,200, against repair or replacement bills of $10,000 to $60,000 or more if problems appear after closing.

What do septic repairs cost?

Angi gives a national range of $500 to $3,000 for septic tank repair, and $300 to $600 for cleaning and pumping, rising to around $1,000 for larger tanks. For contractors, the Attorney General's Home Improvement Contractor Search has a "Sewage/Septic Systems" type of work alongside "Plumbing".

The maintenance calendar puts septic service alongside the rest of the house, sewer line problems covers backups on public sewer, and plumbers are listed on the plumbers directory page.

Sources

How to Care for Your Septic System, U.S. Environmental Protection Agency
On-Lot Septic System Inspections During Real Estate Transactions, Penn State Extension
Water Softening, Penn State Extension
Sewage Program, Bucks County
Sewage & Water, Chester County
Sewage and Water, Delaware County
Permitting & Licensing, Montgomery County
How Much Does Plumbing Repair Cost? [2026 Data], Angi
Home Improvement Contractor Search, Pennsylvania Office of Attorney General
Fix a Leak Week, U.S. Environmental Protection Agency (WaterSense)