It is kind of interesting, it has a backwash that it does automatically when it gets dirty. Although you can bypass it and preform a backwash whenever you need to. You set the time you want it to backwash and when it senses the need for it or after 3 weeks I believe, it waits until the time you set to backwash. I have the backwash set for 1 am on the filter and 2 am for the softener. The backwash for the filter takes about 20 minutes, and you have to secure the backwash hose because it shoots out like a pressure washer.