What You Should Do To Your Pool After It Rains

Written by Michael Dean
November 16, 2023

swimming pool during a rainstorm

While you may test and balance your pool chemicals regularly, sometimes, outside influence can put your chemical levels out of whack. Rain can significantly impact your pool’s pH levels, threatening your swimming pool and all those who swim in it. That’s why it’s important to know what to do when storms come your way.

In this article, I’ll explain how rain affects your pool chemistry, what you should do to check your pool after it rains, how to prepare for the next rainstorm, and more. Let’s dive in!

Main Takeaways

  • Rainwater can affect your pool chemistry because rain is polluted with various gases in our atmosphere, which turns it into acid rain.
  • After rain, you will need to balance your chemicals. After a severe rainstorm, you may also need to shock your pool and/or drain excess water from the pool.
  • Prepare your pool for a rainstorm by removing all pool furniture and equipment, turning off all pool equipment, detaching all gas lines, and balancing the pool water beforehand.

How a Rainstorm Affects Your Pool Chemistry

As a pool owner, it’s your job to ensure that your pool water chemistry is balanced. It’s essential to monitor the pH, alkalinity, chlorine, calcium hardness, and other chemical levels to ensure a pleasant and safe swimming experience. And not to mention, a beautiful, crystal clear appearance!

Did you know that rainwater can cause chemical imbalances?

You might be thinking, isn’t rainwater pure? How could it damage my pool? Well, you’re partially right.

Rain starts at a pure, neutral 7 ranking on the pH scale, a scientific scale that determines how acidic or basic (also called alkaline) water is. But as it’s released from the sky, it becomes polluted by the many different gases spewed into our atmosphere by industrial plants, fertilizers, car exhaust, and other human activities. The two most common gases are sulfur dioxide (SO2) and nitrogen oxide (NO2).

This type of rain is called “acid rain” and is dangerous for humans, the environment, and, you guessed it, your pool.

Acid rain has a low pH level (below 7), indicating it’s highly acidic. The recommended pH level for a swimming pool is between 7.2 and 7.8.

What Happens When a Pool Has Too Much Acid

The more acidic the water, the more corrosive it becomes.

As the acid rain mixes with your pool water, it can begin to lower the pH level and cause your pool’s interior and exterior materials to deteriorate over time (here’s my guide on how to raise your pH level back up). This cutting process is often called “etching,” which can also result from low calcium hardness and damage concrete, gunite, plaster, stone, tile, and other commonly used pool materials.

This increased acidity in a pool can also cause skin irritation for swimmers, along with red and itchy eyes.

What Happens When a Pool Has Too Much Base

On the other hand, rainwater can also dilute the pre-existing chemicals in your pool water and cause your pH levels to rise. When your pool water becomes too basic, it can cause “scaling,” or the build-up of calcium. These white, crusty scales often look like salt and form a white-gray film on the surface of your pool water and may even stain your pool walls.

Eventually, this can lead to other issues such as excessive algae, cloudiness, reduced water filtration, damage to your plumbing system, and rough walls. People who swim in overly basic pool water may experience skin rashes.

What You Should Do to Check Your Pool After It Rains

Now that you understand the impact rain can have on your pool water, what do you do when a rainstorm hits home?

Most of the time, a light rain shower will not disturb your pool water. However, heavier rains are a different story. To be on the safe side, make sure to test the water after any kind of rain. It’s best to check your levels immediately after it stops raining to ensure everything is still balanced. If you find an imbalance, you can adjust the chemicals as you see fit.

You should also check the water level of your pool. The ideal water level should be around the halfway point of your skimmer opening. If the water has risen past that point, you’ll need to lower it, which I’ll go over in-depth below.

Finally, check your skimmer basket! Likely, the rainstorm has dumped a lot of debris into your pool, which your filtration system should be working on clearing. In that case, your basket is likely filled to the brim, so empty it as soon as possible! To lessen the load on your filtration system, you should skim the pool. It might be a good idea to clean or backwash your filter as well.

If your pool water turned cloudy, check out my article on how to clear cloudy pool water after rain for all the steps you should take. Pool water can also turn green after rain.

Should You Shock Your Pool After It Rains?

While you don’t necessarily have to shock your pool after every sprinkle, it can still be beneficial. Pool shock is an efficient and effective treatment that can help keep your pool chemistry balanced and looking great.

Pool shocking is the process of over-chlorinating a pool for a specified amount of time to minimize chemical exposure and eliminate algae, bacteria, and other harmful contaminants.

Pool owners often use pool shock products after heavy use or when the water is contaminated somehow. I recommend shocking a pool after everyone is out of the pool and the sun has set so the shock chemicals won’t evaporate.

Some situations in which pool owners shock their pools include:

  • Opening the pool for the first time in the summer
  • After heavy rain or major storm
  • After a large number of people have been swimming in the pool
  • When temperatures are high for long periods of time

So, if you feel like you need to shock, go for it!

How to Drain Water From Your Pool After It Rains

You may wonder if you should drain water from your pool immediately after it stops raining. Again, this depends on how much rain you receive.

Head outside and examine your pool water level to see what you’re working with.

Was it a minor shower or drizzle? If so, you probably don’t need to do anything but check the levels.

Or maybe you had an intense thunderstorm with heavy rain. Is the water noticeably higher? Are your skimmers completely submerged? Is water splashing out of the pool and overflowing? In this case, you may need to drain some water.

Here are a few simple steps to start draining your pool.

Step 1: Clean the Surroundings

You don’t want any dirt or debris to fall into the water during the draining process. So, be sure to clean the area surrounding your pool (such as the patio or the deck) and remove any debris from the pool, skimmer, and pumps with a net or your hands.

Step 2: Start Circulating

Switch your pump and filter on to start circulating the pool water. This will eliminate any small contaminants that you may have missed.

Step 3: Clean the Pool

This is a good opportunity to clean your pool. Brush the surfaces of your pool and dislodge any debris that might have settled on your walls and steps.

Step 4: Suck It Up

Pull out your pool vacuum or turn on your automatic cleaner (if you have one) to remove all debris from your pool. Keep on vacuuming until the waterline reaches approximately halfway on the skimmer plate. Make sure to turn the filter to “waste” so the excess dirty water doesn’t enter your filter.

Step 5: Drain

Sometimes, you can simply use your pool vacuum to suck up the excess water. However, this isn’t always enough to do the job. In this case, you can use a backwash hose or sump pump hose to finish the task and get your waterline back to normal.

Step 6: Balance

As always, test your pool water to see if any chemical adjustments need to be made, and ensure that your pool does not turn green or cloudy. I recommend checking the pH, alkalinity, calcium, and cyanuric acid levels.

How to Prepare Your Pool For a Rainstorm

By now, you’ve lived and learned. Save some time and effort after the next rainfall by learning how to prepare effectively.

Here are several things you can do beforehand to prevent the amount of work you have to do after the storm has passed.

  1. Make sure to remove all deck or patio furniture and pool accessories from the area surrounding your pool before the storm. Doing so will prevent anything from falling into the pool, blowing away into neighbors’ yards, and causing damage to both your pool and furniture.
  2. Turn off and cover all of your pool equipment (motors, filters, heaters, lighting fixtures, pumps, etc.) to avoid any electrical issues or damage during the storm.
  3. Detach all gas lines from pool heaters to protect you and your family from any sort of dangerous gas leak, deadly carbon monoxide poisoning, or fire.
  4. Balance your pool water before the storm hits to help combat pollutants. This will make for a more straightforward, painless post-storm clean-up and balancing.
  5. Don’t cover your pool. I know your first instinct might be to cover your pool when a storm is coming, but doing so will only damage your pool cover. It’ll be a much easier clean-up to leave your pool exposed.

Bonus Tips:

  • Don’t drain your pool water before a storm, as this leaves the walls and floor vulnerable to damage (especially during high winds).
  • Try to trim tree branches in your backyard to minimize the possibility of them being thrown into your pool.

Get My Free Pool Care Checklist

Download my free, printable pool maintenance checklist to help you accomplish regular pool care tasks for any type of swimming pool.

Something went wrong. Please check your entries and try again.

Frequently Asked Questions

Is it safe to swim in a pool after rain?

Before you jump back in, test the water and clean any debris! If the chemistry is balanced and all the debris is skimmed out of the pool, you are safe to swim in your pool again.

Does rain raise or lower pH in a pool?

Most rainwater in the US is acidic, so more likely than not, rainwater will lower the pH of your pool. This is because, although rain is neutral by itself, it collects a lot of acidic pollutants from the atmosphere.

Should you add algaecide after rain?

I recommend adding algaecide after a rainstorm, but remember; this is not a substitute for shocking the pool. Even better, if you want, you can add algaecide to your pool before the storm to get ahead of the algae and hinder any algae development.

What should I do if my pool is overflowing from rain?

If your pool is overflowing, drain it! Attach a backwash hose, turn your filter to “waste,” and wait until the water level has gone down. Alternatively, use a sump pump.

Should you run your pool pump during a rainstorm?

Yes, I recommend running your pool pump while it’s raining. However, there are certain situations when you may want to turn it off. I cover those in my entire article linked above.

Rain, Rain, Go Away!

Watch the weather for rain and storms, and keep an eye on the local weather report, so you know when they’re on the way. That way, you can adequately prepare your pool and pool area to minimize the amount of clean-up you have to do post-storm. But even after a severe storm, don’t worry! With the above tips and knowledge, you will be enjoying a crystal clear and chemically balanced pool in no time. If your pool is cloudy after a big storm, don’t let anyone swim in it!

Now that you know what to do after the rain is gone, get out there and enjoy some fun in the sun!

Questions? Let me know.

Scroll to Top