It really depends on use, and tank sizes. A good rule of thumb is every 3-5 years. If you sign up for our maintenance contract, we also let you know after each inspection how close you are to needing pumping.
Unless you have already found your favorite pumper, give us a call (206) 491-9049 although we do not pump, we have worked with many pumpers over the past years, and can recommend a good pumper near you, or can even schedule the pumping for you (no additional charge from us).
If you have a gravity system, you only have one tank to pump. If you have a pressure system or pump to gravity, we recommend pumping the pump tank every time you pump the septic. It's not much more to do so, plus it helps keep sludge out of your drain field. If you have an ATU, we recommend pumping the septic & pump tank together, and pumping the ATU as needed. Make sure to fill the ATU with fresh water after pumping though! Call us with questions.
Some pumpers have a flat rate, others charge per gallon. Usually you're looking at $425 + tax to pump a septic tank (up to 1000 gallons).