how to backwash an old pool filter


Author: Poolking - Swimming Pool Equipment Manufacturer

How to Backwash an Old Pool Filter

Maintaining a clean and balanced pool requires regular upkeep of your pool filter. Over time, filters will accumulate dirt and debris, leading to lower filter efficiency and increased pressure. If your pool filter is getting old, it might be time to backwash it. Backwashing your pool filter is an essential maintenance task that you should add to your list of regular pool maintenance. In this article, we’ll talk about the step-by-step process for backwashing an old pool filter.

1. Assess Your Filter Type

The first step to backwashing an old pool filter is to understand what kind of filter you’re using. The two most popular types of pool filters are sand and cartridge filters. The backwashing procedure varies depending on which type of filter you have.

If you have a sand filter, backwashing consists of reversing the water flow through the filter. Whereas cartridge filters require removing the cartridge and hosing it down to remove the dirt build-up.

2. Turn Off the Pool Pump

The second step is to turn off your pool pump. Ensure that the pool pump is switched off before continuing with the backwash. Leaving the pump on during the process will damage the system, and you may have to replace the whole unit.

3. Locate Your Multiport Valve

The next step is to find your multiport valve. This valve is usually located near the pump and filter. In some instances, you might need to remove the valve cover to access it.

4. Turn the Multiport Valve to the 'Backwash' Position

After locating the valve, turn the handle to the 'backwash' position. This action will reverse the water flow and send the water to a waste line, cleaning out the debris that has gathered in your pool filter over time.

5. Turn the Pool Pump Back On

With the multiport valve in the backwash position, turn your pool pump back on. You'll see dirty water flowing from the waste line. Continue running the pool pump until the wastewater turns clear.

6. Rinse the Filter

Once the water going through the waste line turns clear, switch off the pool pump. Move the valve to the 'rinse' position, turn on the pool pump again, and let it run for a few minutes. This rinses the excess debris out of your filter and flushes the water line.

7. Reset the Multiport Valve

After rinsing the system properly, turn off the pool pump and reset the multiport valve. Turn it to the 'filter' position and turn the pool pump back on again.


If your pool water looks cloudy or you notice that the water pressure from your pool jets is weaker than usual, it’s time to backwash an old pool filter. Follow these steps to ensure that your filter operates at optimum efficiency. Proper care and maintenance prolong the life of your pool filter and ensure that the water is clean and healthy for swimming.


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