Those living in El Dorado Hills and Folsom don't often worry about rain -- except for Northern California's "monsoon season" between Thanksgiving and the Spring. Even then, most people only worry about occasional flooding and landslides.
But for homeowners with pools, rain water poses a different kind of risk: pH levels, overfilling, cloudiness, corrosion, and more. At Lakeside Pool Service, we are often called upon to rescue a pool that's undergone serious damage to due to excessive rainfall.
Now that the California rainy season is here, we've created a straightforward guide on the dangers of rain water to your pool. We'll discuss signs of danger, as well as what you can do to avoid damage to your pool.
And as always, we offer affordable weekly cleaning and filtering services that guard your investment year round, regardless of age or weather.
Why rain water is bad for my pool?
Rainwater introduces a variety of challenges for pool owners. While small amounts of rain may have little effect, heavy or prolonged rainfall can:
Dilute your pool’s chemicals, reducing the sanitizer’s effectiveness.
Lower the pH levels of your water, making it more acidic and potentially corrosive.
Introduce debris, dirt, and contaminants that disrupt water clarity and cleanliness.
Encourage algae growth, especially if runoff carries nutrients like phosphates into the pool.
Understanding these risks is key to keeping your pool safe and well-maintained during rainy periods.
Why is chemical balancing so important?
Your pool’s chemical balance ensures the water is clean, safe, and comfortable for swimmers. Rainwater—often with a pH around 5.6—lowers your pool’s pH and alkalinity, making the water more acidic. Over time, this can lead to:
Corrosion of pool surfaces and equipment.
Increased algae growth, as imbalanced water fosters organic buildup.
Cloudy water, caused by disrupted chemical levels.
To maintain a healthy chemical balance, test your pool water frequently during the rainy season and adjust pH, alkalinity, and chlorine levels as needed.
PH level basics - What you need to know
Ideal Range: Your pool’s pH should be between 7.2 and 7.6 for optimal comfort and protection against corrosion.
How Rain Changes pH: Acidic rainwater lowers pH levels, which can corrode metal components and damage plaster or tile finishes.
Adjusting pH Levels: Use pH increasers (like sodium carbonate) to restore balance if levels drop below 7.2. Baking soda can also help raise pH while increasing alkalinity.
Regular testing and adjustments are crucial after heavy rainfall to prevent long-term damage.
Can rain water corrode my pool?
Yes, rainwater can cause both short-term and long-term corrosion.
Knowing the difference between short-term and long-term corrosion damage
Short-Term Damage: Acidic rainwater may discolor or etch metal surfaces, ladders, and tile grout.
Long-Term Damage: Prolonged exposure to acidic water can weaken the structural integrity of your pool, causing cracks or leaks in plaster or concrete finishes.
Preventing corrosion starts with maintaining a balanced pH and inspecting your pool after each storm for visible signs of damage.
Can rain water cause algae to grow in my pool?
Rain itself doesn’t directly cause algae, but it creates the perfect conditions for growth. Rain can:
Introduce nutrients like phosphates from nearby soil or runoff.
Dilute chlorine levels, reducing its ability to kill algae spores.
Increase sunlight exposure if the water isn’t properly treated post-storm.
To prevent algae:
Skim debris from the surface regularly.
Shock your pool after heavy rain to maintain chlorine levels.
Test and rebalance the water chemistry immediately.
What are safety risks of letting rain water collect in my pool?
Your pool is likely to pose a number of safety risks to your landscape and family when left unattended, particularly in California's rainy season.
Environmental risks
Overflowing pools can flood nearby areas, causing soil erosion or property damage.
Unmanaged runoff may introduce hazardous contaminants.
Health risks
Improper chemical balance can lead to bacteria or algae growth, posing risks to swimmers.
Acidic water can irritate skin and eyes.
Structural risks
Excess water pressure on pool walls can cause cracks or leaks.
Overfilled pools strain drainage systems, potentially leading to costly repairs.
Can rain water make my pool appear cloudy?
Yes, rainwater often carries dirt, dust, and organic matter into the pool, which can clog filters and reduce water clarity. If your pool looks cloudy after a storm:
Skim and vacuum the pool to remove debris.
Backwash your filter to improve circulation.
Test and adjust chemical levels to restore balance.
What happens if my pool gets too full of rain water?
When a pool overfills:
Filtration becomes less effective, as skimmers can’t remove debris properly.
Chemical dilution increases, requiring more frequent adjustments.
Overflow may damage surrounding areas or create safety hazards.
When do you drain your pool of excess water?
Draining your pool of excess water is necessary when the water level rises above the skimmer opening, especially after heavy rain. A high water level can hinder your pool’s filtration system from effectively removing debris and maintaining proper circulation. If left unaddressed, this can lead to chemical imbalances, algae growth, and cloudy water.
It’s best to act before another storm to avoid the risk of overflow. However, timing is critical—you should never drain your pool during a rainstorm, as it increases the chances of property flooding and pump damage. Additionally, excessive draining can weaken the pool’s structure, especially for in-ground pools, as groundwater pressure might cause lifting or cracking.
Aim to keep your pool water level halfway up the skimmer. Regularly monitor the water level during the rainy season and plan ahead to prevent overflow, ensuring your pool remains safe and functional.
How do you drain your pool of excess water?
Set your filter to “waste” or “drain” mode.
Monitor the water level carefully to avoid over-draining.
Never drain your pool below the skimmer or the waterline necessary for proper circulation.
How full should your pool be during the offseason?
During the offseason, maintain the water level halfway up the skimmer to ensure proper filtration. If heavy rains are expected, consider preemptively lowering the water level by 1–2 inches to prevent overflow.
Conclusion: How weekly pool maintenance saves your pool and protects your investment
Rainwater poses a variety of risks to your pool, from chemical imbalances to algae growth and structural damage. By understanding these challenges and taking proactive measures, you can safeguard your pool and enjoy it year-round. Regular testing, proper drainage, and professional cleaning services make all the difference.
At Lakeside Pool Service, we specialize in weekly pool cleaning services that protect your investment from seasonal weather changes. Contact us today to keep your pool sparkling, safe, and ready for use—no matter the weather.
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