Photo Credit: Coastal Creek Designs
Springtime showers may bring flowers. It also brings a change in weather: pollen, rain and warmer temperatures. While we in the Lowcountry love spring, there are some challenges these changes introduce into pool maintenance. As the Lowcountry’s leading luxury pool company and your trusted pool maintenance experts, we’re here to answer your questions.
How does rain water impact pool water chemistry?
Short answer: Yes, but not in the way you might think.
When rain falls, it doesn’t just add extra water—it also introduces contaminants, disrupts chemical levels and can leave your pool looking cloudy or green. Rainwater itself may seem harmless, but it’s slightly acidic and can lower pH and alkalinity levels, making the water corrosive. At the same time, rain can dilute chlorine, making it less effective at keeping bacteria and algae at bay.
After a storm, always begin by testing your pool chemistry and balancing the water. In addition to normal balancing procedures, shocking the pool or the addition of a clarifier may be needed to remove any cloudiness.
Do I need to shock my pool after it rains?
As a general rule for DIYers, most of the time, yes. This is especially true after a heavy storm.
When rain dilutes chlorine levels, your pool becomes a breeding ground for bacteria and algae. If the water looks dull or has a greenish tint, it’s time to superchlorinate (shock) it back to life. This can be done by adding granular or liquid chlorine and following the manufacturer’s label instructions. Run your pump and filter for at least eight to 12 hours after shocking, and brush down your pool walls to prevent algae from clinging to surfaces.
For pools that are particularly prone to algae, adding extra chlorine before a storm can help prevent problems before they start. Keep in mind that if the amount of rain is severe, it may dilute what was just added.
How does rain affect pool pH levels?
The effect of rain on your pool’s pH levels depends on your location and the type of rainfall.
In urban areas where rain is more acidic, you may notice a drop in pH, making your pool water more corrosive to pool surfaces, plumbing and equipment. On the other hand, rain that’s rich in minerals—more common in coastal regions, like the Charleston, Hilton Head and other Aqua Blue Pools service areas—can raise pH levels, reducing chlorine’s ability to sanitize effectively.
This is why testing pH and alkalinity after every storm is crucial. If the pH is too low, sodium carbonate (baking soda) can help raise it. If it’s too high, adding muriatic acid or dry acid will help restore balance. Ideally, your pool’s pH should stay between 7.4 and 7.6 for comfortable and clear water.
Should you run a pool pump during heavy rain?
It depends on the severity of the storm.
For light to moderate rain, keeping the pump running can help circulate chemicals and filter out debris before it settles. However, if you’re dealing with severe storms, lightning or hurricanes/tropical storms, it’s safer to turn off the system to protect your electrical components. If you need to leave town during a large storm, ensure the equipment is turned off before you leave. It will remain off until you are able to return.
After the storm passes, backwash or clean your filter to remove any trapped debris and run the pump for at least eight to 12 hours to restore water clarity. If flooding occurs, always inspect your pool’s electrical components before turning the power back on.
What if a pool overflows?
Heavy rain can cause pools to overflow, leading to potential drainage issues and contamination. If your pool is in a low-lying area, excess water can wash dirt, fertilizers and other debris into your swimming space, throwing off chemical balance and increasing the risk of algae blooms. Elevated pools can be an excellent choice for homeowners with these low-lying properties.
If your pool overflows, the best course of action is to turn off any auto-fill systems and use a submersible pump to lower the water level. If your pool has a multiport valve, you may be able to drain excess water directly. Once the water level is stable, shock the pool and rebalance chemicals to counteract contamination.
For long-term prevention, proper deck drainage, French drains and retaining walls can help manage heavy rainfall and protect your backyard oasis.
How do you protect your pool from spring showers?
A little pre-storm prep can make post-storm cleanup much easier.
Before the rain hits, test and balance your water chemistry, adding extra chlorine or stabilizers to help prevent dilution. If you have a pool cover, using it can reduce debris buildup and keep rain from washing contaminants into the water.
Once the storm has passed, your first steps should be:
- Skim and vacuum out debris
- Test and rebalance pH, chlorine and alkalinity
- Shock your pool (if needed)
- Clean the filter and skimmer basket
For more pool care tips, read our “Comprehensive Guide to Maintaining Your Concrete Pool” and explore the articles on our blog.
The bottom line is…
While rain can disrupt your pool’s chemistry, regular maintenance and quick post-storm actions will keep your water crystal-clear and swim-ready all season long.
As the Lowcountry’s most trusted name in luxury pools since 1991, we specialize in custom pool builds and expert maintenance so you can enjoy your backyard paradise, rain or shine.
Does your Aqua Blue pool need post-storm pool service?
Contact us today and let our residential pool builders help keep your water flawless.
Our local team has designed and built pools in various styles for residential and commercial clients from South Carolina’s Lowcountry to Savannah. We are proud to work closely with our clients to create and execute impressive custom projects built to last.