Find Your Septic System and the Records That Go With It

A septic system treats your household wastewater on your own property, and almost all of it is buried. That is what makes it easy to forget, and it is also why the first job is simply knowing where it is. Every later decision, from where to park a trailer to what a service provider needs to find on arrival, depends on that answer.

A typical system has two main parts. Every drain in the house runs to a buried, watertight septic tank, where solids settle to the bottom as sludge and grease floats to the top as scum. The liquid then flows into a drainfield, a shallow covered excavation in the soil, sometimes called a leach field or drain field, where the soil filters and treats it. The U.S. Environmental Protection Agency describes that basic design as a conventional system, and many homes use a variation of it.

Confirm that your home uses a septic system

You may already know from the listing or the inspection. If you don't, the EPA points to a few clues:

• your water or sewer bill shows a $0.00 sewer charge, or you receive no wastewater bill at all
• your home uses a private well, or the water line coming in has no meter
• neighboring homes use septic systems
• the property deed, building permit, or design plans mention an onsite system

Next, look through what you received at purchase. Your home inspection report, the seller's disclosure, and any separate septic inspection report may describe the system and where it sits.

What a seller must tell a buyer depends on the state. In Minnesota, for example, state law requires a seller to disclose in writing how sewage is managed and, for a septic system, to include a map of its location to the extent practicable. The Minnesota Pollution Control Agency notes that the state does not require a compliance inspection at sale, but many county, city, and township ordinances do, and that a seller's disclosure is not a substitute for one. Other states handle this differently, so treat whatever you received as a starting point rather than a complete record.

Ask for the permit drawing and records

The EPA notes that individual septic systems are regulated by states, tribes, and local governments, not the federal government. In many places the local health or environmental department issues the permits, which means it may also hold the design drawing for your system, often called an "as-built," and records of later repairs.

Contact that office with your property address and parcel number and ask what it has on file. Useful items include:

• the as-built or design drawing showing the tank, drainfield, and distances from the house
• the type of system and when it was installed or last permitted
• permits for any repairs, replacements, or alterations
• any operation, maintenance, or inspection requirement that applies to your system type
• the location of any replacement drainfield area set aside on the lot

Records vary by jurisdiction, and older systems may have little or nothing on file. If that happens, ask the office for a list of local septic professionals. The EPA suggests the local permitting authority as the place to find professionals who can help locate a tank and drainfield.

Learn which kind of system you have

The type matters because it changes how often the system needs attention. A conventional system pairs a tank with a soil drainfield. Alternative designs use pumps or gravity to move effluent through sand, peat, constructed wetlands, or other media, and some add treatment equipment. The EPA's list of common types includes:

• Conventional and chamber systems, a tank plus a drainfield built with gravel, stone, or gravelless chambers
• Mound systems, a drainfield built inside a raised sand mound where soil is shallow or groundwater is high
• Aerobic treatment units, which inject oxygen to increase bacterial activity and treatment, and need regular maintenance for the life of the system
• Sand filter and drip distribution systems, which rely on pumps, dosing tanks, and electrical components

The EPA's SepticSmart homeowner guide says alternative systems with electrical float switches, pumps, or mechanical components generally need inspection once a year, and that a service contract is important because of those mechanized parts. If your records show one of these designs, note it prominently. The next step, scheduling inspection and pumping, depends on it.

Find the tank and drainfield from the surface

With a drawing in hand, walk the yard and match it to what you can see. Without one, the EPA suggests following the main plumbing line where it leaves the house. You may find an access riser, which often looks like a black or green disc at ground level. The EPA says the tank is usually about 10 feet from the building, though your site may differ.

Look for lids, risers, or manhole covers at ground level, and for a mound or small hill in the yard, which the EPA notes can mark a drainfield built above the natural ground.

Stay on the surface. Do not dig, pry, or push a probe into the ground looking for the tank. If you can't find it, EPA's SepticSmart guide suggests contacting a septic inspector or pumper to help locate it.

Once you've found the tank and the drainfield, mark them. Stakes, flags, or painted stones at the tank and at the corners of the drainfield let everyone who works in the yard see where not to drive, dig, or build. The Washington State Department of Health advises owners to know where the system is and keep a diagram of its location.

Check the lids without opening them

A lid is the one part of the system most people can reach, and it is the part that protects them. Washington's health department advises owners to know where the lids are, inspect their condition routinely, and keep them secured with bolts, screws, or other locks.

From beside the lid, not on it, look for:

• cracks, chips, or a broken edge
• missing screws or bolts, or a lid that sits loose in its frame
• a gap or a settled, sunken area around the riser
• signs that a vehicle has driven over it, which Washington's health department warns can damage or dislodge a cover

If you find a problem, keep people and pets away from the area and call a septic professional to repair or replace the lid. Washington's health department also recommends a secondary safety device under the lid to catch a child or pet if the lid fails, and teaching children that septic lids are not for playing on or opening.

Put it in your home record

A septic system you have located once should never need to be found again. Add these to your home record:

• a sketch of the tank, lids, and drainfield with measurements from two fixed corners of the house
• photos of each lid and marker, taken from a spot that shows the house for reference
• copies of the permit drawing, the system type, and any maintenance requirement
• the local health department's contact details and the name of any septic professional you use

Knowing where the drainfield is also tells you where to keep vehicles, structures, and deep-rooted plants away. Protecting your drainfield covers what that area needs.

You don't need to understand every part of the system in your first month. Knowing that you have one, where it is, and who holds its records is enough to protect it and to answer the first question any septic professional will ask.