Cloudy Water After Rain

Cloudy Pool Water After Rain - What Causes It?

We’ve been there. One day, your pool water looks perfectly clear. Then, after some rain, you notice your pool water becoming cloudy, almost as if there was a haze building in the water. Have you ever wondered what it is about rainwater that causes your pool to become cloudy?

In this article, we will discuss a few different ways that rainwater can cause your pool water to become cloudy, followed by simple steps you can take to clear up a cloudy pool after rain.

Note: Did you just chlorine shock your pool? If so, check out this guide on cloudy pool water after shock treatment.

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Why Do Pools Get Cloudy After Rain?

There are a few reasons that your pool water can become cloudy after a rainstorm.

Debris Washed Into Pool

Rain can collect tiny particles of dust and other debris from the air and carry it down to the ground, or in this case, into your pool.

Rain acts as a very effective carrier for air pollutants, introducing many airborne particles to your pool water in a short amount of time. These particles can include allergen spores, such as mould or pollen, or fine-dust particles that are present in manufacturing and wildfire smoke. Although these particles are almost impossible to see in the air, when they accumulate in your pool water they can cause cloudiness.

If you have an in-ground pool, you may also get ground runoff during a particularly heavy rain. This happens when rain washes away built up dirt and debris around the edges of your pool, often draining into the pool itself. It’s important to know that the area around your pool does not necessarily have to look dirty for there to be enough microscopic particles capable of causing cloudy pool water.

If your rainstorm was accompanied by wind, you may have accumulated debris that is much larger than microscopic. Organic debris can dissolve in your pool and may harbour harmful bacteria, which can both contribute to cloudy water.

No matter where the debris comes from, when pollutants enter your pool water, they tend to harbour phosphates. Phosphates are organic minerals used in plant fertilisers and found in most organic material.

They are also an essential nutrient needed for certain microorganisms to grow, such as algae. Phosphates along with the microorganisms that feed off of them contribute to making your water cloudy.

Dilution Of Chlorine

The existing chlorine levels in your pool can be diluted by the sudden inflow of water, causing them to drop below the level where they can keep algae and bacteria at bay.

Algae may start growing rapidly in your pool until your correct the levels by adding a chlorine shock.

How to Clear Up Cloudy Pool Water

The first step to take when working to clear up cloudy pool water is to remove any non-microscopic debris from the pool. You may need to use hand-held nets or vacuum the bottom of your pool even if you have a skimmer installed. You should also empty your skimmer baskets, and clean them if necessary.

Next, fix the pool’s water level by draining off any excess water. This can be done using a hose as a syphon. Many pools come equipped with an automatic overflow valve, which makes this step unnecessary.

After adjusting the water level, you will want to do checks on your pool’s chemistry. We recommend checking chlorine levels, pH, and alkalinity after a rainstorm. A standard 4-in-1 Test Kit contains everything you’ll need to test these properties.

Make any adjustments you need to make to return your pool to its appropriate chemistry. This includes chlorine shock treatment if necessary.

After this is done, you will want to use a phosphate reducing agent to get rid of excess phosphate that algae can feed on. This can be followed up with a clarifier, to drop most of the suspended cloudy material to the bottom of the pool.

The Algon Pool Clarifier is a great option for clearing up a cloudy pool without affecting the overall pH.

If you live in an area that gets rain often, you may want to take a more preventative approach to keeping your pool water clear after rain. The Crystal Cube Plus Blocks can be added to your skimmer basket and actively work to neutralise phosphates and other haze-causing minerals from your pool while your pump is running.

After using a clarifying agent, it’s important to let your filter run for a minimum of eight hours, or as is otherwise indicated on your product’s packaging. Keeping your water well-circulated allows your clarifying agent to work more effectively.

We recommend running your filter for an absolute minimum of eight hours every day to keep your pool adequately clean. This along with other regular maintenance can help to reduce the chances of cloudy water in the future.


Although cloudy pool water after rain can be a nuisance, it’s something that can be fixed with little hassle compared to other issues. If it’s something that you encounter often, there are products that can help you prevent cloudy water after rain in the future.

Do you have any more questions about the causes of cloudy pool water or how to get rid of it? Leave us a comment down below, we’d love to chat!

Louis from Pool Advisor


A chemical engineer by trade, Louis is committed to debunking myths in the pool industry by explaining the underlying chemistry and making it accessible to all.