How To Backwash A Pool


You may have a pool in your backyard, and you’re starting to notice some sediment accumulating in the filter. You may also be experiencing water discolouration.

Proper pool maintenance can be tricky to get down pat. Sometimes, figuring out the source of a pool problem can feel like pulling teeth. You bought all the products, raked all the debris and added all the right chemicals, and still, your pool is not looking as impressive as it should. What so many pool owners neglect is their pool filter. Treating and cleaning your pool when you have a blocked pool filter can be time consuming and pointless. Your pool filter is responsible for removing sand, dust, debris, and other contaminants already trapped inside the pool filter to prevent damage to the pool pump. When these contaminants are not prevented, they may clog the pool’s filter system and reduce its efficiency, making the frequency in which you need to clean increase. 

So how often should you backwash a pool? In this post, we’re going to show you step-by-step when and how to backwash a pool filter to ensure that the rest of your maintenance is optimised.

What Type Of Filter Do You Have?

There are three types of pool filters: Sand Filter, Cartridge Filter and Diatomaceous Earth Filters (DE Filters for short). Each of these has its pros and cons, particularly when it comes to cleaning.

Filter, Backwash, Rinse, Circulate, Closed, and Waste are the six settings on a standard pool filter multiport device. Frequent vacuuming can cause a large amount of soil and sediment to get trapped in the filter, causing it to clog, which, if left unchecked, will decrease the filter's capacity to clean and hinder the water flow, placing further pressure on the pool.

Cartridge Filter: 

Cartridge filters


With a cartridge filter, the process isn't too complicated; simply remove the cartridge and clean it manually. Cartridge filters cannot be back washed merely by reversing the water flow in the pool's filter system because they were not designed for reverse water flow. When these filters get filthy, they must be washed by hand.

DE Filter: 

With a DE filter, the process is a little different. You will have to backwash this filter.

Sand Filter: 


Sand Filters

Cleaning a sand filter is a bit more complex, but don't let that deter you into not doing it as much as you can. When you do get around to it, it can just make the mission more challenging.

When to Backwash Your Pool

We recommend backwashing a pool at least once a month as a general practice. When the filter's gauge reads ten psi above the usual operating range, though, it's time to do it. There are a few indicators that it's time to backwash a pool. Cloudy water may also mean that the filter needs to be cleaned.

Backwashing frequency is determined by a variety of factors, including how much the pool is used and how much sediment it collects. Backwashing your sand filter should be done at least once a month, but this can increase during the season. 

Are There Signs That My Pool Needs Backwashing?

Some indicators that your pool might need backwashing can include 

  • Increased water pressure, which means that the system is under strain, 
  • limited water flow due to a backlog of bacteria and sediment, and 
  • cloudy water, which indicates that extra debris is working its way back into the pool

How to Backwash a Pool:

Backwashing a pool filter is a relatively simple enough process. Quite obviously, it means you send a burst of water backwards through the filter to clean out debris. This is how you do it:

Backwashing is the process of reversing the flow of water into the pool's filter, flushing the filter medium (sand or DE), and then expelling the polluted water into the drain.

When you've done backwashing for a sand filter, it's a good idea to clean the filter to avoid any leftover blowback into the pool. By rinsing the filter, it resets the sand in its original location for optimal filtration, just as the backwash raises and flushes it.


  1. Start off by switching off the filter system.
  1. Attach the backwash hose to the waste port on the filter.
  1. Choose “Backwash” on the multiport valve, or simply open the backwash gate for a push-pull valve.
  1. Restart the filter machine and allow it to run for two minutes.
  1. Restart the filter mechanism and select “Rinse” on the multiport valve, or manually rinse for a push-pull valve.
  1. Restart the machine and let it run for about a minute.
  1. Switch off the filter system once more.
  1. Return the multiport valve to the “Filter” position, and for the push/pull valve, simply close the valve.

Where Should You Go For All Your Pool Equipment Needs?

We offer a variety of swimming pool supplies at Pool Assist, including robotic pool cleaners and pool filters. We also offer a range of services to clean and refresh your pool, including filter backwashing.  Our specialist technicians will provide competent maintenance and upgrades so you can be assured that your pool filter and other facilities are in good working order all year. 

Give us a call if you have any problems with your pool! For pool filters, pool filter parts, suction cleaners or to book a service for one of our experienced technicians to come out and sort the problem for you, contact Pool Assist today on 1300 857 302, or send through an enquiry