Residential Services

A Guide to Septic Cleaning
How Often Do You Pump Out A Septic Tank?

The table shown below lists the recommended septic tank pumping frequency according to septic tank capacity and household size. The frequencies were calculated to provide a minimum of 24 hours of wastewater retention assuming 50 percent digestion of the retained solids.

Common septic tank pumping frequency mistakes

  1. Failure to pump the septic tank frequently enough: leading to an early drainfield failure and costly repairs
  2. Pumping or cleaning the septic tank too frequently, wasting money (though you’re wasting a lot less money than the cost of a new drainfield.Some septic pumping contractors and some other “experts” give a fixed rule of thumb that serves their own interest, such as “pump your septic tank every year” or “pump your septic tank every two years” or in a case we know about in Minnesota, “pump the septic tank every couple of months or after you’ve had a lot of visitors”.

    It would be smarter to pump the septic tank before or both before and after heavy use if we know the septic system is marginal. Pump the tank before a period of heavy usage to avoid a sewage backup during the heavy usage interval and afterwards to get back to normal usage levels.

    Contractors may give this advice without first having actually considered any information about the septic system capacity, level of usage, age, or other conditions. It’s a great example of “OPM” or “other people’s money” – spending someone else’s money to reduce your risk that they’ll complain that your advice wasn’t safe enough.

  3. Pumping the septic tank with the fantasy that doing so will “fix” a clogged or failed drainfield. All you really gain is a few days of toilet flushing before the tank has re-filled.

Actually inspecting the septic system, diagnosing any problems or failures, and inspecting conditions inside the septic tank will tell us whether the tank is being pumped at the correct frequency.

The removal of septic waste by cleaning the septic tank is a critical step in septic system care as it extends the life of the septic field. Even if you don’t care how septic systems work you need to know when to clean the septic tank by pumping out septic waste. Using the septic tank cleaning frequency table just below, simply look up your tank size and number of building occupants to see how often the septic tank should be cleaned. Later in this article we list other factors that can increase or decrease the recommended pumping rate.

Table I. Septic Tank Pumping Frequency in Years

Septic Tank Size

Gallons

Household size – Number of Occupants
1 2 3 4 5 6 7 8 9 10

Septic Tank Pumping Frequency in Years

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 0.3
900 11.0 5.2 3.3 2.3 1.7 1.3 1.0 0.8 0.7 0.5
1000 12.4 5.9 3.7 2.6 2.0 1.5 1.2 1.0 0.8 0.7
1250 15.6 7.5 4.8 3.4 2.6 2.0 1.7 1.4 1.2 1.0
1500 18.9 9.1 5.9 4.2 3.3 2.6 2.1 1.8 1.5 1.3
1750 22.1 10.7 6.9 5.0 3.9 3.1 2.6 2.2 1.9 1.6
2000 25.4 12.4 8.0 5.9 4.5 3.7 3.1 2.6 2.2 2.0
2250 28.6 14.0 9.1 6.7 5.2 4.2 3.5 3.0 2.6 2.3
2500 30.9 15.6 10.2 7.5 5.9 4.8 4.0 3.5 3.0 2.6

NOTES to the Septic Tank Pumping Schedule Table:

  • Numbers in the septic pumping table indicate septic treatment tank pump out in frequency of every nn years for conventional septic tanks, and assuming for year-round occupancy of the residence. (This data does not pertain to simple holding tanks which retain all solid and liquid waste with no treatment no effluent disposal system.)
  • * These septic tank sizes are below the minimum size allowed in Pennsylvania and other jurisdictions. Florida septic tank pumping rules and Ohio septic tank cleaning rules may be more demanding.
  • Minimum septic tank sizes: Under current Pennsylvania law a 900 gallon septic tank is the minimum size that must be used for a home with three bedrooms or less. If six people reside in a three-bedroom house, the tank should be pumped every 1.3 years. If the same system serves a family of two, the tank would be ready for pumping every 5.2 years. Systems installed before the current rules and regulations were implemented may need to be pumped more often, perhaps every year or less.
  • Garbage disposers will increase the frequency of pumping. For example, if this same three bedroom house with six residents had a garbage disposal and was generally producing a higher volume of wastewater, the pumping frequency would be calculated as follows: 1.3 years – [(0.2) x 1.3 years] = 1.0 year. For more analysis of the effect of garbage disposers on septic systems.
  • Typical Septic Tank Pumping Costs: A typical fee to pump a septic tank is $200. to $300 to pump a septic tank up to 1000g in size, provided that the tank pumping access port has been uncovered and is readily accessible.If the septic pumping contractor needs to find the septic tank and then excavate the septic tank pumping access opening, expect to pay an additional $350. to $400. provided that no extraordinary measures are needed. Prices vary somewhat by region. A part of the fee you’re paying your septic pumping contractor is the cost to dispose of the septage.
  • For an explanation of the meaning of sewage levels in the septic tank and how that information informs septic tank pumping frequency,
  • Portions of this information were provided by the Penn State College of Agriculture – Cooperative Extension. We have edited and added to the original septic tank pumping guideline material based on research and field experience testing, inspecting, and installing septic systems and based on study of other reference sources on septic system maintenance and design.