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Cleaning a Swimming Pool After Heavy Rain

Heavy rains can overwhelm your pool by significantly altering the chemical balance with the introduction of new water. Storms and flooding can also introduce many other new things into your pool. Dirt, debris, rain water, and even lightning can all affect the overall water chemistry of your pool and put a strain on your equipment. A quick cleanup is essential to minimize any potential issues like algae, cloudy water, staining, or excessive filter pressure. The following checklist will help you clean your pool after a rain storm. The main points you need to remember are to:

Pool leaf skimmer

Skim the pool to remove excess debris.

Leslie's Pool Shock

Shock the pool and run the filtration system for at least 12 hours.

Pool water balance

Test and re-balance pool water. Remove phosphates.

Items Needed for Rain & Storm Cleanup in Pool

Before you get started, or even as soon as the first sprinkle of rain, make sure you have all the right supplies on hand to maintain your pool water. Once the skies are clear and blue again, it's time to get your water clear and blue again, too.

How To Clean a Swimming Pool After Rain

1. Brush & Skim the Pool

First things first, you'll need to thoroughly skim and brush the pool. Skimming large debris from the pool with a leaf rake alleviates the stress on your filtration system, and stirring up dirt by brushing makes it easier for the system to filter out. Brushing also prevents algae spores and dirt from adhering to pool surfaces. Remember to clean out your skimmer and pump baskets to allow for steady water flow throughout the system.

If there's a lot of dirt and sediment left at the bottom of the pool, remove it manually with a pool vacuum or use an automatic pool cleaner. The cleaner the water is to start with, the more efficiently your sanitizer can work.

BONUS TIP: If heavy rainfall has left your water levels too high, you can remove the excess water with a submersible pump or by turning the multiport valve on your sand or DE filter to the "waste" setting.

2. Shock & Filter the Water

In the evening, shock your pool with a product such as Leslie's Power Powder Plus or Leslie's Chlor Brite. Shocking helps sanitize any contaminants or materials that were introduced to the water during the storm.

Run your system for at least 12 hours to ensure proper filtration and circulation. This removes dirt and debris, and also assists with circulating the chlorine throughout your pool. The day after shocking the pool, check the PSI on your filter pressure gauge. If the pressure is sitting 8-10 PSI higher than normal, you'll need to clean the filter.

3. Test & Balance Pool Water

Test your water with an at-home test kit, or bring a sample to your local Leslie’s store for a free AccuBlue® water test. Rain water and other debris affect pool chemistry, most notably the pH and total alkalinity. Be sure to take a look at calcium hardness, metal content, and total dissolved solids, as well. If these numbers fall outside of normal ranges, prevent scale and stains from forming by adding a sequestering agent, such as Leslie's Stain and Scale Prevent.

It is also recommended to test for phosphates, as this typically spikes after a heavy rainfall. This is included with the Leslie's AccuBlue® test, or you can use a specialized at-home test kit. Lightning increases the nitrogen in the air, which cause grass and algae to turn greener. These photosynthetic organisms then create a problem for chlorine. A chemical such as Leslie's Perfect Weekly will remove phosphates in the water and starve algae of food, therefore inhibiting their growth. Perfect Weekly also contains enzymes, which break down organic contaminants and help your sanitizer work more efficiently. It's a good idea to also add a preventative algaecide, such as Leslie’s Algae Control.

If your pool water is still cloudy 24 hours after adding any needed chemicals and/or cleaning your filter, you can add a water clarifier like Leslie’s Ultra Bright Advanced or Leslie's Clear Aid to help expedite the cleaning process.

BONUS TIP: No power? No problem! You can either use a battery-operated robotic pool cleaner or a leaf bagger to help keep the water clean and circulating until power is restored. If any equipment was damaged during the storm, you'll find a bunch of helpful tips on our other blog post: How To Maintain a Pool With Damaged Equipment.


If any questions or problems arise, please contact a local Leslie’s professional to help you clean your pool after a rain storm. Our customer care team is standing by to answer all your pool care questions.