How to Backwash a Sand Filter: A Step-by-Step Guide

Backwashing your pool’s sand filter is a crucial maintenance task that helps keep your pool water clean and clear by flushing out accumulated debris and dirt from the filter. Here’s a detailed guide on how to backwash a sand filter effectively, ensuring your pool remains in top condition. This process typically takes about 15 to 20 minutes and should be performed every few weeks or as needed, depending on your pool usage and the amount of debris your pool collects.

Step 1: Gather Your Tools and Prepare the Area

Before you begin, make sure you have everything you need close at hand. You’ll need:

  • A backwash hose
  • Access to the filter system

Ensure the area around the filter is clear and accessible. Extend and straighten your backwash hose, making sure it is directed to an area where it will not cause erosion or flood your garden.

Step 2: Turn Off the Pool Pump

Safety first! Always turn off the pool pump at the circuit breaker before changing the filter settings to prevent any accidental starts while you are working on the equipment. This step is crucial to avoid damage to the pump and for your safety.

Step 3: Attach the Backwash Hose

Attach the backwash hose to the filter’s backwash port. If your setup does not have a dedicated backwash hose, you will need to connect one securely. Ensure it is tightly fitted to avoid leaks and that it leads to an appropriate drainage area.

Step 4: Set the Filter Valve to “Backwash”

Locate the multiport valve on the top or side of your sand filter. This is typically labeled and can be turned to different settings. Rotate the valve handle to the “Backwash” position. Make sure to perform this step slowly and carefully to avoid any damage to the valve mechanism.

Step 5: Turn On the Pump

Go back to the circuit breaker and turn on the pump. The water will begin to flow through the filter, backwards, lifting and rinsing the sand inside. Watch the sight glass on the filter or look at the water coming out of the backwash hose; it will initially appear dirty.

Step 6: Run the Pump Until the Water Clears

Let the pump run for 2-3 minutes, or until the water in the sight glass (or coming out of the backwash hose) runs clear. This process flushes out the dirt from the sand filter back into the drainage area through your hose.

Step 7: Turn Off the Pump

Once the water runs clear, turn off the pump at the circuit breaker again to halt the backwashing process.

Step 8: Set the Filter Valve to “Rinse”

Change the setting on your filter’s multiport valve from “Backwash” to “Rinse.” This setting will help to stabilize the sand again after it has been lifted during the backwash.

Step 9: Rinse the Filter

Turn on the pump again and let it run for about 1 minute. This process will clear out any dirt or debris that is left in the pipes.

Step 10: Return the System to Normal

Turn off the pump. Set the multiport valve back to the “Filter” position. Turn the pump back on for normal filtering. Check around the system for any leaks or issues.

Step 11: Clean Up

Disconnect the backwash hose, rolling it up neatly for storage. Ensure the area around the filter system is clean and dry.


Backwashing your sand filter regularly is essential for keeping your pool’s filtration system working efficiently and your pool water sparkling clean. Remember, the frequency of backwashing depends largely on pool usage and the amount of debris your pool collects. Always monitor your pressure gauge, and backwash whenever the pressure rises 8-10 PSI over the normal operating level.

With this guide, you should be able to handle backwashing your sand filter confidently, ensuring your pool remains a clean and enjoyable part of your home.


Contact Us

Big Becks Contact Us