People – curious people – sometimes like to see what the septic tank pumper is pumping out of their yards. They are often surprised to see that the stuff that gets pumped out of the tank looks – and smells – mostly like water. More surprisingly, as is often the remark, “the tank is so full!”
Septic tanks are actually designed to work in a mostly full manner – typically, the “operating level” is a foot or so down from the top of the tank. The tank is a watertight container that accepts the household wastewater and allows it to settle out. By capturing the wastewater between the level that enters the tank (the inlet) and the level of the water that exits the tank (the outlet), the tank provides the primary treatment of the wastewater by allowing the solids in the wastewater to sink and become sludge, and the fats, soaps, oils, and greases float and are called scum.

A typical two-compartment tank with access risers and covers to grade and an effluent filter on the outlet.
Over time the sludge and scum build up requiring the tank to be emptied periodically. The time between recommended pumps-outs varies depending on many factors including but not limited to family size, system size, and water use. Our technician will make recommendations and notes regarding what was found during the pump out.
Finally, a full tank should never be confused with an overflowing tank. If you know you have an effluent filter, you’ll want to check and clean your filter first. If your septic tank shows signs of overflow – ponding or pooling over the tank – you should call us.
We can help.
(978) 772-1600
For the more curious: here is animated, interactive model of how a typical septic system works.
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