How to find your septic tank (and the lids)

1. Ask the county or health department for the septic permit and as-built drawing. Many are searchable online by address.
2. Check the home's paperwork: inspection reports, old pumping receipts and the property survey often mark the tank.
3. Find where the main drain leaves the house — a cleanout pipe outside, or the large pipe going through the basement or crawl space wall.
4. Walk out from that point in a straight line. Most tanks are 10 to 25 feet from the house; codes commonly require at least 5 to 10 feet.
5. Probe the ground every couple of feet along that line with a thin metal rod, pushing gently. A tank lid or top feels flat and solid a foot or two down.
6. Once you hit it, probe around to find the edges, then dig carefully at the ends to find the lids. Most tanks have one at each end, or one per compartment.

• A rectangular patch where snow melts first or the grass is greener or browner than around it.
• A slight depression or mound roughly 5 by 8 feet.
• A plastic riser or concrete lid at ground level — someone may have already done the work.
• A vent pipe sticking out of the lawn, or an inspection port near the tank.
• An area that has never had anything built, planted or parked on it.

A soil probe is the simplest and most reliable tool. A metal detector can find the steel reinforcement in some concrete lids or a metal handle, but not a plastic tank. Plumbers and septic companies can push a small transmitter through the drain line from a cleanout and trace it from above with a locator — the fastest method when there are no records.

The top of the tank is commonly 4 inches to 3 feet below the surface, depending on the slope of the lot and how deep the house drain leaves the foundation. Tanks deeper than that usually have risers. If yours has buried lids, installing risers to grade costs $300 to $800 per opening and means you'll never have to dig for them again.

Septic companies typically charge $100 – $400 to locate a tank, sometimes waived if they pump it at the same visit. Digging to each buried lid adds $50 – $200. Mark the lids once they're found — a stake, a flat stone, or a note in your records with measurements from two corners of the house.

Pumping cost and the extras→

Lids are heavy and gases inside are dangerous. Never lean into an open tank or let anyone enter one, keep children and pets away, and never leave a lid off or loosely placed. If a lid is cracked, cover it with something that bears weight and replace it.