Is It Safe to Swim in a Pool After Rain?

Have you ever wondered if it’s safe to swim in a pool after it rains? On first thought, it seems fine: rain can top up the water that evaporated, helping you save on the water bill. Unfortunately, rain will do more harm than good.

is it safe to swim in a pool after rain
Photo Credit: CC BY-NC-SA 2.0

Rain can bring contaminants and debris into the water which will use up the free chlorine in the pool. Rainwater can further affect the water chemistry by decreasing your pool’s total alkalinity, calcium hardness, and pH levels which can render the chlorine ineffective. Therefore, it is not safe to swim in a pool after rain without first treating it.

In this article, we’ll discuss how rain can impact your pool’s water chemistry and the steps you should take to maintain optimal water quality.

Factors Affecting Pool Safety After Rain

Contaminants and Debris

After a rainfall, contaminants and debris can make their way into your pool. Rainwater can wash dirt, leaves, and other debris that can accumulate in your pool, affecting its cleanliness. Rain can also introduce bacteria, viruses, and other pathogens into the water. Clean your pool after it rains to ensure a safe and healthy swimming environment. You can do so by:

  • Skimming the surface to remove floating debris
  • Using a pool vacuum to clear out any settled dirt and debris
  • Checking and cleaning the pool filters

Changes in Water Chemistry

Rainwater is acidic in nature and can significantly alter the pH balance and chemistry of your pool water. This change in pH can make the water more acidic, causing it to irritate your skin and eyes. In addition, it can reduce the effectiveness of chlorine, making it harder for the pool to kill bacteria and germs. To combat this issue, you should:

  • Test the pH, alkalinity, and chlorine levels of your pool water after rain
  • Adjust the pH and alkalinity levels as needed
  • Shock the pool with the appropriate sanitizer to restore its effectiveness

Overflow and Pool Damage

Heavy rains can cause your pool to overflow, which can lead to potential damage to the pool structure and the surrounding area. Overflowing water can erode the soil around the pool, potentially compromising its structural integrity. You must properly manage your pool water level after rain to avoid any damage. Some steps you can take include:

  • Draining excess water using a submersible pump or by setting your pool pump to “waste” or “backwash”
  • Checking for any signs of damage or erosion around the pool and fixing them promptly
  • Setting up proper drainage systems in your backyard to prevent pooling of water and erosion

Assessing the Pool’s Condition

How can you determine your pool’s condition after it rains? The key factors to consider are the pool’s visual appearance and the water’s chemical balance. Let’s explore these aspects in more detail.

Visual Inspection

Start by checking the pool’s surface for any debris that the rain might have carried in, like leaves or branches. Removing any debris will not only improve the pool’s appearance but also increase the water visibility. You can use a skimmer or a pool net to remove this debris effectively.

Next, take a look at the pool’s water clarity. If the water appears cloudy or discolored after the rain, it may indicate an imbalance in the water chemistry or the presence of contaminants. In this case, it’s best to avoid swimming until you have tested and adjusted the water’s chemical balance.

Chemical Testing

Testing the water’s chemistry after rain is crucial for maintaining a healthy and balanced pool environment. Rainwater is acidic, which can decrease the pool’s alkalinity and affect chlorine levels, negatively affecting its ability to kill bacteria and germs.

  • pH levels: Low pH levels can sting a swimmer’s eyes or nasal passage and cause dry, irritated skin. High pH levels can lead to irritated eyes, redness, rashes, and dry skin. Add a pH increaser such as soda ash and aim for a pH level between 7.2 and 7.6 for optimal comfort and safety.
  • Alkalinity: Ensure the alkalinity is within the range of 100-150 ppm (parts per million) to help maintain a stable pH level and prevent fluctuations. Adding baking soda can increase alkalinity without increasing pH too much.
  • Chlorine levels: Proper chlorine levels will vary depending on your pool’s size, outdoor temperature, and usage, but generally, you’ll want to maintain a level between 1-3 ppm.
  • Calcium levels: Rainwater is soft water, which will reduce the calcium hardness of your pool water. This is beneficial if your water is hard to begin with (over 400 ppm), but it becomes an issue if your calcium hardness is less than 200 ppm.

Test your pool using a pool testing kit or test strips. Whenever you notice imbalances, adjust the chemicals accordingly to ensure a safe swimming environment. To do so, keep the following chemicals stocked up:

  • Salt or chlorine
  • Alkalinity
  • Calcium Increaser
  • Phosphate Remover
  • Shock
  • Muriatic Acid
  • Cyanuric Acid
  • Algaecide

Remember to check your pool’s condition after every rainfall, regardless of its intensity.

Steps to Make the Pool Safe After Rain

After experiencing rainfall, you need to take specific steps to ensure your pool is safe for swimming. Here’s how:

Address Pool Damage

Inspect your pool for any damage that may have occurred during the storm. Look for potential issues like cracked tiles, ripped liners, or malfunctioning equipment.

Check your pool’s pump and filter system, ensuring it’s functioning correctly. If you identify any damage, patch it up or consult with a pool professional for assistance.

Reduce the Water Level

If water has managed to make its way into your pool, then the first thing you need to do is to bring down the water level until it is around halfway past the skimmer level. You can drain your pool by setting your pump to waste or backwash.

Remove Debris

Particles like leaves, dirt, or trash that may have fallen into your pool during the rain need to be removed. It’s best to remove debris early on before it sinks to the pool floor later.

Start by using a long-handled pool skimmer to collect and remove any large debris floating on the surface.

Next, vacuum the pool floor to remove sediment and smaller particles. Check and clean out the skimmer baskets and filters as well, as the debris accumulated during the storm can clog them.

You can remove debris as the pool pump is draining the excess water to maximize your time.

Turn on the Filter System

Once the water level is back to normal, set your pump to “filter.” You’ll want to have the water circulating again as you move on to the next step.

Balance Water Chemistry

Rainwater can affect your pool’s chemistry, with pH levels potentially becoming more acidic. To ensure a healthy swimming environment, test and adjust your pool’s chemical balance. Use a pool test kit to find the current levels of:

  • pH: Ideally should be between 7.4 and 7.6
  • Chlorine: Aim for 1.0 to 3.0 ppm
  • Total alkalinity: Maintain between 80 and 120 ppm
  • Calcium hardness: Keep within 200 and 400 ppm

Add the necessary pool chemicals as required until they reach the ranges indicated above, following the manufacturer’s guidelines for your specific pool products.

Preventing Future Issues

By taking precautionary measures, you can minimize the impact of rain on your swimming pool and ensure its safety.

Install a Pool Cover

Using a pool cover can help protect your pool from debris and contaminants brought by the rain. It prevents excess rainwater from entering the pool, thus reducing the need for extensive cleaning and balancing of chemicals after the rainfall. Cover up the pool whenever it’s not in use.

You should specifically buy a pool cover and not a tarpaulin. While tarps are water-resistant, they will eventually let water through and this can upset your pool’s water chemistry as discussed above. Pool covers are waterproof and will keep all rainwater out, in addition to its other benefits.

Regular Maintenance

Performing regular maintenance on your swimming pool is essential in maintaining water quality and cleanliness. When you are keeping up with the pool maintenance, you reduce the chances of encountering any issues after it rains. Monitor the pH balance and chlorine levels in your pool consistently to ensure it remains safe for swimming.

  • Check your pool’s pH and chlorine levels at least once a week.
  • Use a quality, accurate pool testing kit to monitor these levels.
  • Adjust the chemicals as needed to maintain the recommended values for a healthy pool.

Prepare Your Pool for Heavy Rain Beforehand

Knowing the weather forecast, particularly if a storm is coming, can help you prepare your pool for upcoming rain. Before the storm arrives, you can take some proactive steps to minimize its impact:

  1. Skim and clean the pool to remove any dirt or debris
  2. Shock the pool 1-2 days before the storm in anticipation of the incoming contaminants from rainfall.
  3. Lower your pool’s water level by 1-2 inches to accommodate incoming rainwater and prevent overflow.
  4. Secure all pool accessories and furniture to prevent them from getting damaged or causing damage during the storm.
  5. Turn off all pool equipment at the breaker, such as pump motors, pool heaters, automation systems, to prevent damage to them.

By following these tips and being proactive with your pool’s care, you will minimize the amount of work you need to do after it rains to treat your pool.

Frequently Asked Questions

How long after it rains should you wait to swim?

A general rule of thumb is to wait at least 24-48 hours after a rainstorm before swimming in your pool. This allows time for any contaminants that may have entered the pool to be properly diluted or filtered out.

Some sources may recommend waiting longer than 48 hours, with some suggesting waiting up to 72 hours after raining before swimming. Additionally, even if you wait the recommended amount of time, you should still test your pool’s water to ensure that it’s safe for swimming.

What chemicals are in a pool after it rains?

Rain will significantly raise the amount of phosphates, nitrates and other organic contaminants into the pool. It will also dilute and decrease the levels of the chemicals already in the pool. Rain may also contain trace amounts of metals such as copper and iron which can cause discoloration in your pool.

Should you shock your pool before or after rain?

Some pool owners may choose to shock their pool before a rainstorm to prepare for the influx of contaminants that may enter the pool during the rain. This can help to ensure that the pool’s chemical balance is properly maintained and that any contaminants that do enter the pool are quickly eliminated.

You can also shock it afterwards to deal with the contaminants that entered the pool during the rain. No matter if you shock your pool before or after it rains, you need to test your pool’s water to determine if it’s safe to swim in or not.

Why does my pool turn green after heavy rain?

Your pool can turn green or cloudy after heavy rain because the pool chemicals that keep it clean have been diluted which leads to algae growth. Furthermore, contaminants will be introduced that can result in algae growth and microorganisms in your pool. There may also be debris such as dirt that is decreasing the water’s visibility.

Should you turn off the pool pump when it’s raining?

You do not need to turn off the pool pump when it’s raining under normal circumstances so that it can continue to filter out dirt and debris. However, a thunderstorm can cause damage to your pump, in which case switch it off at the breaker to protect it.