Water Resources Center
OSTP

The Water Resources Center is affiliated with the College of Food, Agricultural and Natural Resource Sciences and University of Minnesota Extension.

How Often to Pump Your Septic Tank


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Your septic tank must be cleaned or "pumped" periodically to remove the solids that accumulate in the tank. How often you need to clean your septic tank depends on its size, the number of people using the system, and how careful you are about using it.

In new homes, clean it prior to occupation. Clean it again within six to twelve months to make sure it is functioning properly. Wastewater from painting, varnishing and other construction activities can reduce bacterial activity in new systems.

Once a system is operating properly, the tank should be cleaned every one to three years. Never go more than three years between cleanings. The Septic System Owner's Guide can help you decide how often is right for you.

Minnesota codes require that a licensed professional do cleaning through the tank's manhole. Proper cleaning removes the scum and sludge. Liquid contents are pumped back and forth from the truck to the tank until all solids are liquefied and removed. If floating scum is left in the tank, solids may enter the drainfield. Cleaning leaves a black film on the sides of the tank and a small amount of liquid on the bottom. These contain bacteria, which allow the tank to begin working again. There is no need to add a starter after cleaning.

The contractor should inspect the tank to make sure baffles are in place and functioning properly. Contractors cleaning the tank through four or six "inspection pipes" often do not remove all solids and may damage baffles. Insist that your contractor clean the tank through the manhole. Most tanks have one or two manholes that are often buried below the ground surface. A little digging may be necessary to find them.

Remember, a few dollars spent every one or two years on proper cleaning can save you big dollars on repairs, which can run an unexpected $2,000 to $10,000.

The Septic System Owner's Guide is available from your local Extension office.