Septic Pumping Interval Calculator

Estimate how often to pump your septic tank from tank size and household size, using the published extension table (Mancl 1984 via Ohio State Extension).

Tank size unknown? It's often on your county permit or a past pumping receipt. Pennsylvania's code, for example, requires at least 900 gallons for a 3-bedroom home.

Estimated years between pumpings (year-round residence). Source: Ohio State Extension AEX-740, from Mancl, K. (1984), *J. Environmental Engineering* 110(1):283-285. Pump more often with a garbage disposal.
Tank (gal)	1 ppl	2 ppl	3 ppl	4 ppl	5 ppl	6 ppl	7 ppl	8 ppl	9 ppl
500	5.8	2.6	1.5	1.0	0.7	0.4	0.3	0.2	0.1
750	9.1	4.2	2.6	1.8	1.3	1.0	0.7	0.6	0.4
1,000	12.4	5.9	3.7	2.6	2.0	1.5	1.2	1.0	0.8
1,500	18.9	9.1	5.9	4.2	3.3	2.6	2.1	1.8	1.5
2,000	25.4	12.4	8.0	5.9	4.5	3.7	3.1	2.6	2.2
2,500	31.9	15.6	10.2	7.5	5.9	4.8	4.4	4.0	3.0

Frequently asked questions

Is the calculator exact?

No. It reads the published extension estimate for the nearest table row. Actual sludge buildup varies, so check sludge depth or follow your pumper's advice.

Sources

Penn State Extension: Septic Tank Pumping
Ohio State Extension AEX-740 (Mancl 1984 table)

Last checked: October 21, 2026