How to Find a Buried Septic Tank
You can't pump a tank nobody can find. Many older tanks have lids buried under grass, gravel or a flower bed, and the person who knew where it was sold the house years ago. Here's how to narrow it down before the truck arrives.
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We pass your request to independent local septic professionals, and a local septic pro will contact you directly. They'll reach out as soon as they can; timing depends on their schedule. If it's an emergency, say so in the form so the contractor sees it.
Start With Records
The University of Missouri Extension publication EQM104F suggests starting with paperwork: if you don't know where your tank is, a previous homeowner, the county health department or a pumper's records may have the answer. Also check:
- A home-sale inspection report, which often includes a sketch or measurements
- Any permit or as-built drawing from when the system was installed
- Old pumping receipts, which sometimes note where the lids are
Records in Boone County
- Boone County Resource Management handles onsite permits. For remodels that add bedrooms or bathrooms, Boone County Resource Management asks for documentation such as a soils evaluation or a copy of the original permit, which suggests where records live. Ask the county what it has for your address.
- Lagoon homes: the tank is usually between the house and the lagoon. Boone County's Boone County lagoon requirements cover lagoon placement, not tank location, but the lagoon itself is an easy landmark.
- Newer tanks: Boone County requires newer tanks to have a manhole riser to the surface, so a newer system may not need any digging at all.
Follow the Sewer Line
MU Extension's method is simple: in the basement or crawlspace, find the sewer pipe leaving the house and note which direction it goes through the wall. Then go outside and, in that direction, probe the ground with a narrow metal rod, or dig, about 10 to 20 feet from the house. MU notes the tank is usually within about 2 feet of the surface, and that settling, depressions or lusher grass can hint at the tank and the field.
The DHSS onsite system owner's manual adds a caution: start downslope from the house, but if your system has a pump, some parts may be upslope. Look for inspection ports, tank or valve access, and alarm panels as clues.
Probe Carefully
- Probe gently. You're feeling for a hard, flat surface, not trying to break through.
- Call 811 before you dig, so buried utilities are marked.
- Mark what you find with a flag and measure from two fixed points, such as the corners of the house. MU recommends sketching a map with those distances.
Safety
- Never open or enter a tank. DHSS warns that tank gases or a lack of oxygen can be fatal.
- Old or damaged lids can give way. Keep children and pets back, and don't stand on a lid you're unsure of.
Let the Pumper Find It
Most pumpers locate and uncover lids as part of the job. Ask about it when you request service, and ask what it costs, since published guides list extra charges when lids must be dug up. Risers that bring the lids to the surface make every future visit simpler. We mention them so you can ask about them, not as an offer.
Related: septic tank pumping, septic inspection, septic pumping cost.
Request service with our short form
We pass your request to independent local septic professionals, and a local septic pro will contact you directly. They'll reach out as soon as they can; timing depends on their schedule. If it's an emergency, say so in the form so the contractor sees it.
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