According to HomeAdvisor, the average reported cost to clean or pump a septic tank is $437 as of 2014. The pricing ranges from a minimum of $200 to a maximum of $800.
The cost to clean a septic tank can vary based on issues such as the size of the tank, the time since the last cleaning and the prevailing prices in a community. Cleaning of a tank should be completed every one to three years based on the number of people and usage patterns on the property. Additionally, more frequent cleaning should be scheduled for owners who have a small tank.