When Should I Pump My Septic Tank?
Answer four questions, get a pump-by date. The math comes from university extension-service pumping schedules (Mancl 1984) — the same tables behind our pumping guide.
About every 2.6 years
How we got there:
The rule behind this: pump when combined sludge and scum reach one-third of the tank’s liquid depth — the standard trigger across extension literature (Penn State, Thurston County WA, UNL). These schedules assume year-round occupancy and no garbage disposal; the disposal adjustment is an estimation proxy, disclosed above. Read the full pumping guide for the table this is built on, what moves your interval, and how to find your tank size.