Rain’s Effect on Pool Water

Rain's Effect on Pool Water

When you own a swimming pool, you should know that plenty of things can throw off its water chemistry and, as a result, the cleanliness and enjoyability of your pool. One of those things is water — that is, water that falls from the sky. 

Yes, rain can alter your pool’s chemistry considerably, depending on how much rain falls and what that rainwater carries with it on its way down from the clouds. But aside from altering its chemistry, rain can also have other effects on your pool water that you may not anticipate. 

How exactly does rain change pool water chemistry, and what else can it do to your swimming pool? Read on to find out. 

Altered Water pH

Properly taken care of pool water should have a pH that falls somewhere between 7.2 and 7.8 (7.4 to 7.6 is ideal though). If the water’s pH gets too high, swimmers may suffer from skin rashes. If it gets too low, eye redness and pain may result from water exposure. Maintaining an appropriate pH range is also important for maintaining the integrity of the pool itself — too high or too low of a water pH can damage the walls of a pool over time. 

When rain falls, it can throw off the water’s pH, depending on the pH of the rain itself and the amount of precipitation that occurs. While a little rainfall may not alter the pH of a pool significantly, it may become just one in a number of factors that alter pool pH and make the water unpleasant to swim in. 

In some cases, heavy, prolonged rainfall can alter the water’s pH enough that you may need to add a pH increaser or reducer to restore the appropriate balance. You’ll need to test the water chemistry to determine whether either of these additives is appropriate for your pool, or you can have a pool maintenance pro handle that job for you. 

Decreased Total Alkalinity

Rainwater can decrease your pool water’s total alkalinity, as it’ll naturally dilute the water over time. Since rain has a pH that’s roughly neutral (it’s usually around a seven on a scale of 0 to 14), it can significantly decrease your pool’s alkalinity if enough of it falls even in a single day.

To fix this issue, you’ll need to add an alkalinity increaser to the water. If you don’t, the water will become overly acidic and corrosive and could damage the interior surface of your pool over time. Low-pH water may also damage other metal and rubber components of your pool with prolonged exposure. 

Reduced Cyanuric Acid Levels

Maintaining the proper cyanuric acid level in your pool (which is somewhere between 20 to 50 ppm) is important because this compound bonds free chlorine in the pool water. That bonding action serves to prevent the all-important chlorine from evaporating too quickly. 

When rainwater accumulates in your pool, it’ll naturally dilute the cyanuric acid in the water, and when the sunshine returns, your pool’s chlorine level could take a nosedive. If it does, the water won’t remain sanitary, and swimmers could experience a number of unpleasant skin, eye, and respiratory symptoms after they get out of your pool. 

Increased Chlorine Demand

Whether you own a chlorine or saltwater pool, rain will dilute your pool’s water and, therefore, its chlorine concentration. If you want to maintain a sanitary pool, you’ll either need to add more chlorine or salt to the water, depending on the type of pool you own, to bring that chlorine level back to where it’s supposed to be. 

Alternatively, you can add chlorine or salt before it rains, provided you accurately estimate the amount of rain that will fall. If you add too much, you’ll end up throwing off your pool’s water chemistry and causing additional problems. 

Algae Growth and Cloudy Water

Rainwater probably won’t be a direct cause of algae growth, but it can introduce phosphates to the water, which provide food for algae to grow. And because rainwater dilutes the pool chemicals that keep the water clean and clear, it’ll probably also be an indirect cause of cloudy water. 

You’ll need to test and rebalance your pool’s chemical levels after each storm if you want to maintain crystal clear and pleasant-to-swim-in water. 

Need Pool Maintenance Service Near Rockwall, TX?

Want to keep your pool water in the best condition possible all swimming season long? Don’t want to deal with the hassle of maintaining your pool yourself? Then get in touch with our team at Community Home Services to set up a pool maintenance schedule with our swimming pool pros! 

We specialize in all things swimming pools, including water testing, chemical balancing, pool repair and leak detection, pool supply service, and more. Our knowledgeable technicians have the experience necessary to take excellent care of your pool, and we offer several tiers of maintenance plans to suit virtually any need.

To schedule pool service or repair or learn more about our many home services, feel free to give us a call today at 972-722-1200. You can also contact us online, and we’ll get in touch promptly with more information!