Does rain affect fibreglass pools? If you happen to be someone who has this question on your mind, we’re sorry to let you know that it does – and not just fibreglass pools. Lots of rain can affect almost every type of swimming pool. However, don’t start sweating because we’ve got all the solutions to the pool and rain riddle in this post. So sit tight and read on!
Key Takeaways
- Heavy rain can alter pH, alkalinity, calcium hardness and TDS, especially if runoff enters the pool.
- Prioritise a quick post-rain checklist: remove debris → run filtration → test water → rebalance chemicals.
- If runoff has entered the pool, treat it as higher risk (solids + contaminants) and vacuum/clean sooner.
- Use your filter correctly: cartridge vs sand “waste / drain” steps differ — follow the method that matches your setup.
- Watch for water under/around the pool after prolonged rain; check the inspection/standpipe and pump out if needed.
- Before storms, focus on prevention: protect electrical equipment, take algae-prevention steps, secure outdoor furniture — and don’t drain the pool.
How does rain affect swimming pools?
The answer to this question lies in the fact that rainwater has acidic properties due to gas emissions from industrial activities. These properties are known for altering the chemistry of pool water. From the levels of alkalinity to pH balance – various aspects of the pool water chemistry can change when exposed to excess rainwater.
Rainwater may also enter a swimming pool via sources like decks and landscapes, and this is even worse for the pool compared to direct exposure. This ‘run off’ water may contain a variety of solids, and these solids can change not just the pool water’s pH and alkalinity levels, but also its total dissolved solids (TDS) and calcium hardness.
A swimming pool may also experience overflow issues if excess rainwater accumulates inside it. Overflows can be messy affairs, and it’s a hassle to clean them up, particularly if they contain debris. Additionally, if you’re living in an area that experiences frequent rains, rainwater may also make its way down underneath the pool, which can present its own set of problems.
Why runoff is usually worse than direct rain
Direct rainfall mainly dilutes your pool water. Runoff (from decks, landscaping, garden beds, and surrounding surfaces) can introduce fine sediments, organic matter, and contaminants that increase the load on your filter and can throw water balance off faster. If your pool was cloudy after a downpour, runoff is often the reason.
What to check first after a downpour
As soon as it’s safe:
- Water level (especially if the pool is close to overflowing)
- Visible debris (leaves, twigs, soil)
- Water clarity (cloudiness indicates suspended solids / filtration load)
- Then move straight into the post-rain steps below (filtration + testing + balancing).
Do you know the affects rain water has on the quality of water in your swimming pool? If not find out everything there is to know right here.
While rainwater-associated pool problems won’t occur if the pool water’s exposure to rainwater is limited, they can become a menace if there’s a cloudburst or storm. However, there are ways of maintaining your swimming pool even if you live in an area that experiences frequent rains or faces the fury of the monsoons every year.
Tips to minimize rainwater damage
A helpful rule: clean first, circulate second, balance third. If you rebalance chemicals before removing debris and circulating the water, you’ll often waste product and end up retesting again anyway.
Here are some of the things you can do to minimize the impact that rains have on your fibreglass pool:
- Keep a log of your pool water’s chemistry: We’ve already mentioned it twice but can’t stress it enough – rainwater changes pool water chemistry. That’s why you should make it a habit to check the chemistry and keep a log. It’s important that you do this not just during the months of monsoon but also after every storm that happens outside of the monsoon period. If you’re pressed for time, approach a local swimming pool service provider to do it for you. Through regular checks, even the most minor changes to the pool water’s chemistry can be detected before there’s too much contamination. Professional maintenance providers can adjust the pool water chemistry by adding the necessary chemicals.
If you don’t already track results, even a simple note in your phone works (date, weather event, pH, alkalinity, chlorine, and any adjustments). Over time you’ll spot patterns, like “after heavy rain, pH drops and chlorine demand spikes,” which makes future storm recovery much faster.
- Make filter-based changes: There are two types of pool filters – cartridge filters and sand filters. If your pool has the former, connect the hose of the pool to the 3-way-valve. Next, place the hose in the drain that’s dedicated to dealing with the stormwater. Follow it up by turning the valve’s handle, which will lead to the water being diverted through the hose. End the process by making necessary water level adjustments by turning on the pool pump. If the pool has a sand filter, change the multi-port valve to the waste setting mode. Next, bring water levels down until there’s efficient re-circulation by turning on the pool pump.
After heavy rain, expect the filter to load up quickly. In the first 24–48 hours, it’s common to need more frequent cleaning/backwashing/rinsing than usual until clarity returns. If water stays cloudy after circulation, manual vacuuming can help remove settled debris so the filter isn’t doing all the work.
- Pump out rainwater collected under the pool: If you live in a region where rainfall is intermittent, you aren’t likely to face this issue. However, if the rains are heavy and regular, a portion of the water can make its way under the pool and settle there, which may lead to soil contamination and other environmental damage. All you have to do is check the inspection pipe or the standpipe to find out if there’s any water accumulated underneath the pool. If you detect accumulated water, you can pump it out either using a Slurpy pump or a combination of skimmer box and pool pump. If you don’t know what a Slurpy pump is, you can go to your local hardware store to understand its uses and buy one. This step is easy to overlook, but it matters in regions with repeated heavy rainfall. If water sits beneath the pool for extended periods, it can contribute to ground saturation issues. A quick check of the inspection/standpipe after major storms is a good habit.
Preparing your fibreglass pool for heavy rain
The steps we mentioned just now are all about post-rain maintenance. But there are some steps you can take to prepare your fibreglass pool as well, which include the following:
- Pay attention to the electric equipment: Pool pumps and other electric equipment may sustain damage if they are exposed to heavy rainfall. Check the weather forecast regularly to know when the next rains are likely to hit. Keep the pump indoors until the rains are over, and bring it out only when it’s dry.
- Keep algae invasions at bay: The potential of algae invasions significantly increases during periods of heavy rain. To prevent algae invasions from occurring, it’s best to add an algaecide to the pool water before the rainfall begins.
- Protect outdoor furniture: Sustained heavy rainfall along with robust winds can really put your outdoor furniture to the test. While the furniture may not have anything to do with the pool water, it certainly has a lot to do with the overall pool setting and ambiance. So, gather all outdoor furniture and secure them well so that they stay intact no matter how hard it rains.
- Draining your pool is a bad idea: There’s a common misconception that draining a swimming pool before a storm is effective at protecting the pool from rainwater. However, don’t fall for it, as heavy rain for extended periods can lead to your pool liner being cracked and lifted due to a rise in the water table. Letting the water be inside the pool helps in maintaining its stability.
So, that’s about it for this post. We hope that you learned a thing or two about maintaining and protecting your pool from the effects of heavy rain. If you live in a dry region, these tips probably won’t be of much help to you. However, if your pool is subject to heavy rain consistently throughout the year, it’s time to take action. If you need any assistance our team are more then happy to help, you can call us directly on 1300 324 909 or you can fill out our quote form to get in contact with our agents today!
Key Takeaways
Does heavy rain affect fibreglass pools?
Yes. Heavy rain can alter water chemistry and introduce contaminants, especially when runoff enters the pool.
Why is runoff worse than direct rainwater?
Runoff can carry solids and debris from decks/landscaping into the pool, affecting pH/alkalinity and increasing pool contaminants.
What should I do first after a heavy downpour?
Remove debris, run the pump/filtration to circulate the water, then test and rebalance chemistry.
Should I change how I use my filter after heavy rain?
Yes. The page outlines different steps for cartridge vs sand filters, including diverting/setting to waste and adjusting water level to restore circulation.
Can heavy rain cause overflow problems?
Yes. Excess rain can cause overflow and messy debris cleanup, particularly in storm conditions.
Should I drain my pool before a storm?
No — draining is called out as a bad idea and may lead to pool liner cracking/lifting due to changes in the water table.
What if water collects under my pool after repeated rain?
Check the inspection pipe/standpipe and pump out accumulated water (e.g., with a Slurpy pump or suitable setup) to reduce ongoing issues.