When should I pump my septic tank??

Well, the easy answer is the old recommended 3-5 years, but this is based on averages. By definition more of us are average than not! Unfortunately, there are still a lot of the "not so average" out there that donít quite fit the mold. This leaves us with a very difficult question to answer!

1st, there are a number of questions to ask.

1. What is the size of your tank?

2. How many people use the system?

3. Do you use a garbage disposal?

4. What kind of soil do you have - good drainage or poor?

5. How old is the system?

6. How much are you willing to risk damaging your drainage system?

- Do you have plenty of property for new drain lines?

- Do you have sewer available to hook-up to?

- Do you have money to do the above?


Let's say the average system (3-5 year pump interval) consists of the following:

1,000 gallon tank, 3-4 people, no garbage disposal, and average performance drainage system of less than 20 years of age.

If you have a small (500-750 gallon) system - subtract a year

For more people using the system (5+) - subtract a year.

For a single compartment tank, - subtract Ĺ year.

For a two compartment tank Ė add Ĺ year.

For garbage disposal use - NO MORE THAN 2 YEARS TOTAL (of course this depends HIGHLY on the amount of use. I've seen 2 people pack out a 1,000 gallon tank in 1.5 years!!!)

For an older system or a system with poor drainage Ė donít go beyond 3 years (except for larger tanks with 1-2 people; {balancing factors})

These are at best ballpark figures. Thus, as you can see, precise estimates are not possible without a track record of current system performance or homeowner usage habits. The best thing is for you to know your system and your usage habits. For a new system or new homeowner, pump early and base you next pumping interval on the solids accumulated. Make notes of any changes in system use: babies, college kids, party lifestyle, or anything that would increase or decrease the input to the tank.

The best way to tell if a tank needs pumping, if one is ambitious: measure the scum solids level. For most systems this requires digging up an access lid. Measuring the scum level is fairly easy. It is somewhat more difficult measure the sludge level.


Keep in mind that no drainage system will last forever. Some last a short time with no apparent abuse, while others, with obviously excellent drainage, last many years under abusive conditions. But, all things being equal, systems that are pumped regularly will last far longer than systems that are not pumped. You donít buy a new vehicle and run until failure. But you do preventative maintenance and change the oil in your engine to make it last. It is a very common misconception that if it works, leave it alone. If youíre lucky, it will only be a pump job. But itís too late to reverse the damage and there is a considerable chance that your system will be damaged to the point that it will no longer function adequately.