How to find your septic tank

Step 1: Check the records

Ask it for the as-built drawing (record drawing) and the permit, which may show where the tank is.

In Arkansas, call the county health unit and ask for the Onsite Environmental Specialist. It helps to know the year the home was built, the subdivision name and lot number, and the original owner or developer.

A previous owner or the company that last pumped the tank may also have a record of its location.

Sources: US EPA, Frequent Questions on Septic Systems (last updated Mar 11, 2026); Arkansas Department of Health, Onsite Wastewater FAQs (no date shown); University of Missouri Extension, EQM104 Household Wastewater: Septic Systems and Other Treatment Methods (Home*A*Syst Fact Sheet 4, no date shown)

Step 2: Follow the sewer line

Find where the main sewer pipe leaves the house, in the basement or crawl space, and note which way it goes through the wall.

Go outside on that side. The EPA says the tank is usually about 10 feet from the building. University of Missouri Extension suggests probing 10 to 20 feet out along the line of the sewer pipe.

Sources: University of Missouri Extension, EQM104 Household Wastewater: Septic Systems and Other Treatment Methods (Home*A*Syst Fact Sheet 4, no date shown); US EPA, Frequent Questions on Septic Systems (last updated Mar 11, 2026)

Step 3: Probe gently

Push a narrow metal rod into the ground along that line. The top of the tank is usually within 2 feet of the surface.

Settled spots or depressions, or extra-green grass, can hint at the tank or the field.

Source: University of Missouri Extension, EQM104 Household Wastewater: Septic Systems and Other Treatment Methods (Home*A*Syst Fact Sheet 4, no date shown)

Step 4: Look for lids and risers

Many tanks have an access riser at the surface. The EPA describes it as a black or green disc.

Newer Oklahoma systems must have cleanout openings that reach at least 2 inches above ground with a locked or tool-secured cover, so they are easier to spot.

Tanks usually have openings over the inlet and outlet, plus larger central access ports for pumping.

Sources: US EPA, Frequent Questions on Septic Systems (last updated Mar 11, 2026); Oklahoma DEQ, OAC 252:641 Individual and Small Public On-site Sewage Treatment Systems (amendments effective 9-15-24); Penn State Extension, Septic System Basics (Kibuye, updated Sep 16, 2024)

Step 5: Find the drain field

The distribution box and drain field are usually downhill from the tank, though some systems pump wastewater uphill to the field.

Some systems sit in a raised mound, which the EPA notes can be a visible sign of a septic system.

Sources: University of Missouri Extension, EQM104 Household Wastewater: Septic Systems and Other Treatment Methods (Home*A*Syst Fact Sheet 4, no date shown); US EPA, Frequent Questions on Septic Systems (last updated Mar 11, 2026)

Step 6: Mark it and map it

Once you find the tank, sketch a map and measure from the tank opening to at least two permanent points, like a house corner.

Penn State Extension recommends installing risers to the surface and marking the tank's location so it is easy to find for future pumping.

Sources: University of Missouri Extension, EQM104 Household Wastewater: Septic Systems and Other Treatment Methods (Home*A*Syst Fact Sheet 4, no date shown); Penn State Extension, Septic Tank Pumping (Jarrett, updated Jul 21, 2023)

When to call a professional, and safety

If you still cannot find it, the EPA says a septic professional can walk the property and locate the tank and drain field.

Never climb into or lean into a septic tank. The gases can kill.

Sources: US EPA, Frequent Questions on Septic Systems (last updated Mar 11, 2026); University of Missouri Extension, EQM104 Household Wastewater: Septic Systems and Other Treatment Methods (Home*A*Syst Fact Sheet 4, no date shown)