How to backwash a swimming pool filter? Step by step guide

Backwashing a pool filter is an essential maintenance task that every pool owner should be familiar with. It's a process that involves reversing the flow of water through the pool filter to remove any accumulated dirt and debris from the filter media. If you're new to pool ownership or just want to learn more about this important task, this article will provide you with a detailed overview of what backwashing is, why it's necessary, and how to do it properly.

What is Backwashing?

Backwashing is a process of reversing the flow of water through a pool filter to flush out any accumulated dirt, debris, and other contaminants. Pool filters work by trapping and removing these unwanted materials from the water as it circulates through the system. Over time, the filter media becomes clogged with these particles, reducing its ability to filter the water effectively. Backwashing is a simple and effective way to remove this build-up and restore the filter's efficiency.

Why is Backwashing Necessary?

Backwashing is necessary for two primary reasons: to maintain water quality and to protect the pool equipment. As a pool filter becomes clogged with dirt and debris, it can no longer effectively remove these materials from the water. This can lead to cloudy or dirty water, as well as an increased risk of bacterial growth. By backwashing the filter regularly, pool owners can ensure that the water stays clean and clear, making it safer and more enjoyable to swim in.

Additionally, a jammed pool filter can put a strain on the pool's circulation system, potentially causing damage to the pump and other equipment. By removing this buildup, backwashing helps to prevent equipment failure and prolongs the life of the pool filter.

Note: It is crucial to backwash a pool filter to prevent potential damage. Failure to backwash the filter when necessary can cause the collected bacteria in the sand to harden, ultimately leading to the filter bursting.

A sand filter is an essential component of a swimming pool's filtration system. Over time, the sand in the filter becomes clogged with debris and particles, reducing its efficiency. Backwashing your sand filter helps clean out the debris, ensuring your pool water stays clean and healthy. In this article, we'll walk you through the steps of how to backwash a sand filter using a multiport valve. 

How to backwash a sand filter for swimming pool? 

Before you get started, you'll need a backwash hose. This is a specialized hose that is designed to fit onto the backwash port of your sand filter. You can purchase a backwash hose at most pool supply stores.

Using multiport valve for backwashing the sand filter Swimming pool filter backwash

Here are the 10 simple steps you should follow:

  1. Attach the backwash hose securely to the backwash port of your sand filter.
  2. Turn off the filter system to ensure safety.
  3. Rotate the multiport valve to the BACKWASH position to initiate the process.
  4. Switch on the filter system to allow water to flow through the backwash port and hose.
  5. Wait for about a minute, or until the water runs clear.
  6. Turn off the filter system again for the next step.
  7. Move the multiport valve to RINSE to clean the sand filter.
  8. Switch on the filter system again and let the water flow through the backwash port and hose for approximately 30 seconds.
  9. Turn off the filter system for the final time.
  10. Rotate the multiport valve back to FILTER position to resume normal filtration.

Important Note: To prevent any damage or water leakage, it is crucial to avoid turning the multiport valve handle while the pool filter and pump is operating. Doing so may cause the rubber diverter gasket located inside the valve to dislodge or break, resulting in water leaking from unintended ports while the filter is still running. 

Backwashing process - FILTER position Backwashing process - BACKWASH position

Best Practices for Backwashing a Pool Filter

Backwashing entails reversing the water flow through the filter to flush out any accumulated dirt or debris, restoring the filter's efficiency.

But when should you perform this task? The frequency of backwashing depends on factors such as the pool size, filter size, and the quantity of debris in the pool. A general rule of thumb is to backwash the filter when the pressure gauge on the filter rises 8-10 psi above its standard reading, indicating that the filter is clogged and requires cleaning.

Another indication that the filter requires backwashing is a weak water flow into the pool, usually because of a blocked filter preventing the water from flowing freely. However, be careful not to backwash the filter too frequently, as this may reduce its effectiveness and shorten its lifespan. Backwashing eliminates some of the filter media, which is vital for the filter to operate effectively.

How frequently should you backwash your pool filter? This depends on your pool's size and the amount of debris in it. A small pool with low usage may only require backwashing once a week, while larger pools with higher usage and more debris may require more frequent backwashing, possibly every few days.

Apart from backwashing, it's crucial to regularly clean the filter by removing any accumulated debris in the filter basket or skimmer. This reduces the filter's load and ensures it operates efficiently.

In summary, backwashing your pool filter is an essential component of pool maintenance that ensures clean and safe swimming water. To achieve this, you should backwash the filter when the pressure gauge on the filter rises 8-10 psi above its standard reading, while avoiding too frequent backwashing, which can reduce the filter's effectiveness and shorten its lifespan. Regularly cleaning the filter by removing accumulated debris is also necessary for optimal filter performance.

How to Dispose of Filter Backwash Water

Filter backwash water is a by-product of the filtration process used to remove impurities from water. This water contains contaminants and particles that have been trapped in the filter, and it must be disposed of properly to avoid environmental harm. Here are some tips on how to dispose of filter backwash water safely:

Follow local regulations. Check with your local authorities to determine the regulations governing the disposal of filter backwash water in your area. Different states and municipalities have different rules, so make sure you comply with the requirements.

Reuse the water. If possible, try to reuse the filter backwash water instead of disposing of it. This water can be used for irrigation, flushing toilets, or cleaning outdoor surfaces. However, it is important to note that the water may still contain some contaminants, so it should not be used for drinking or cooking.

Filter and treat the water. If you cannot reuse the filter backwash water, you can filter and treat it before disposal. This can be done using a settling tank, a sand filter, or a chemical treatment process. Once the water has been treated, it can be discharged into a sewer or septic system.

Use a holding tank. If you cannot filter and treat the water, you can collect it in a holding tank and dispose of it in accordance with local regulations. Holding tanks are often used in areas where there is no access to a sewer or septic system.

Dispose of the water properly. If you need to dispose of the filter backwash water, do so in a way that minimizes the environmental impact. Avoid dumping the water in streams, rivers, or other bodies of water. Instead, discharge the water into a sanitary sewer or a septic system. If neither of these options are available, consult with your local environmental agency for guidance on proper disposal methods.