Plumbing, Heating and Pool Repair Guides

How To Backwash A Swimming Pool Sand Filter


How To Backwash A Swimming Pool Sand FilterA swimming pool is like the human body, it cannot function without a filtration system. The sand filter in your swimming pool has a very important job, which is why you need to care for it properly and check that it is working on a regular basis. The sand filter in your swimming pool cleans the dirt, leaves and bacteria that may enter your pool each day.

If you did not have a working sand filter than no one would want to step foot in your pool. It would be both unattractive and unsafe for you friends and family to swim in. “Backwashing” your sand filter is one of the most important things you can do to keep your filtration system working properly. You should backwash your sand filter every 2 weeks to make sure your swimming pool is clean and ready for your guests to swim in. It is very easy to do and if you follow the step-by-step directions below you should be able to backwash your swimming pool sand filter in no time!
Pool Filter Sand
The sand that is in your sand filter needs to be clean in order for your pool to stay clean and for your water to flow in the right way. When your sand filter is working normally the flow of water will reverse itself every once in awhile which helps keep the sand clean. Before you do anything make sure the swimming pool filter is turned off and that the circuit breaker is also off. Make sure all electrical wires are unplugged and are not near the water to avoid electrical shock. If your sand filter is a top mount you will need to find the handle sticking out on either the top or the side of your filter and set it to the “BACKWASH” setting. When you find the handle you will need to both push down on it and rotate it clockwise slowly until it is in the “BACKWASH” position. Now turn the pool filter back on. At this point there should be murky water flowing out of the backwash line. Let the filter backwash for about 5 minutes and monitor it to make sure that water continues to come out of the filter. When the water is no longer cloudy and dirty looking and starts to run clean then you are done backwashing the sand filter. You can now turn the pool filter back to the off position.

After you have finished backwashing you will need to use the same handle you used for the backwash and push down and turn it clockwise until it reaches the “RINSE” position. Turn the filter back on again and let it run for about 30 seconds. The rinse cycle takes all the sand that you just released into the pool and collects it and puts it back into the bottom of the filter and gets it self ready for proper filtration. Turn your pool filter off again. Now press the same handle back down and turn it clockwise until it is back in the “FILTER” position that it was in to start with. Turn your pool filter back on. It should now be in normal filtration mode. After you do the whole backwashing process you will notice that your PSI on your pressure gauge will have gone down. Most swimming pool sand filters run at 10-25 PSI. If for example your pressure went down to PSI after backwashing you should do another backwash when the pressure has increased by 10 PSI to a total of 20 PSI.

Now that you have backwashed your swimming pool sand filter you can pat yourself on the back and teach all of your friends and family how to do it. Pretty soon you will be the person that everyone comes to for advice on how to keep your pool clean and functioning properly. Do not forget that backwashing your swimming pool sand filter is not a one-time thing. Makes sure that you repeat this process once every 2 weeks to keep your pool healthy and beautiful.


  1. Our maintenance man went on vacation this past Tuesday. Today is Thursday. Before he left, he vaccumed the pool and backwashed the thing. The problem is that water is still running out of a drain pipe outside the equipment room. I think the lever is in the wrong position. HELP!! PLEASE!! I guess I will pay attention to what he does next time. I have to fill the pool with water every afternoon. I am wasting water like crazy…Of course the manual is nowhere to be found.

    Thanks for any help you can give me. The maintenance man has been with us for three years and gone on vacation many times…


  2. Just check the position the handle on your pump is in. Check and make sure that your drains aren’t opened either.

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