Can You Use Rainwater To Fill Your Pool?

If you own a pool, you know that keeping it in great shape can be a real challenge — and finding shortcuts where you can often means spending less time and money on maintenance. One shortcut you may have considered is whether you can use rainwater to fill your pool. But is that a safe option?

It’s not recommended to fill your pool with rainwater. Rainwater in the US is acidic, meaning it can corrode parts of the pool and will certainly throw off the chemical balance in the water. However, a special rain harvesting system can be used to make rainwater safe for use.

Let’s take a closer look at the potential to use rainwater to fill your pool and more generally how rain water affects your pool water.

Should You Use Rainwater to Fill Your Pool? 

Rain drop to the swimming pool

You shouldn’t use rainwater to fill a significant part of your pool — at least not without taking some steps first. Rainwater isn’t ideal to swim or bathe in, and it’s certainly not good for a pool, which needs very specific things to thrive.

The first thing that will happen if you use rainwater is that the chemical balance of your pool will be thrown off. That can make it unsafe to swim in, and it can also damage the pool equipment. As rainwater in the US is acidic, having too much of it in your pool can be corrosive.

That doesn’t mean you need to worry about a little bit of rainwater getting into the pool. It’s pretty normal for that to happen. However, if there’s heavy rain, you should use a pool cover (on Amazon). You should certainly never let your pool fill up with rainwater deliberately.

Can You Make Rainwater Safe for Use?

If you’re determined to use rainwater to fill your pool, there is a way to do so. You can collect rain from your roof it in a storage tank and run it through the correct filtration system to make it safe for your pool.

You also need to make sure your roof is free from hazardous materials and pollution before you make the decision to collect water from it. An inspection is key, as otherwise, you could make your pool unsafe to swim in.

When you have the water collected in the storage tank, you can then use it to top up your pool when you need to.

Although the initial construction of this system can take a lot to set up, it then should run pretty smoothly, making it a worthwhile investment if you can afford the initially high cost.

Does Rainwater Affect Your Pool’s pH Levels? 

With any luck, a small bit of light rain shouldn’t affect your pool’s pH levels. However, a significant amount will definitely lower the pH and make the water more acidic. That means you’ll need to take some time to restore the pool’s chemical balance.

You can take preventative measures to keep your pool in good shape. If there’s a rainstorm coming, make sure you cover the pool to prevent as much rainwater from getting in there as possible. If rain does get in there, test the pH level using test strips (on Amazon) before getting back in.

Can You Use Rainwater to Help Conserve Water in the Pool?

If you use the above method of collecting rainwater for your pool from the roof, then you can conserve water this way. If you need help, some contractors should be able to set the system up for you.

A rainwater harvesting system typically costs upwards of $8,000, so it’s no small project.

What’s the Easiest Way to Fill a Pool?

Since using rainwater is not the most affordable or simple option, there are easier ways to fill your pool. If convenience is your priority, a heavy-duty garden hose is the best way to go about it.

You’ll then have to add chlorine to the water and make sure the chemical levels are appropriate before you go ahead and get in. 

Filling a saltwater pool involves a similar method, though you’ll just have to add salt instead of chlorine and ensure your generator is working.

What Happens if Too Much Rainwater Gets in the Pool?

Rain drops in the swimming pool

If too much rainwater gets in the pool and you don’t correct it before letting people swim, you could find that the swimmers experience some medical problems. They may experience rashes on their skin and irritation in their eyes or ears. Those with respiratory issues may be more affected.

In order to prevent such issues, you’ll have to add some soda ash (on Amazon) to rebalance the pH of the pool and keep testing it until you’re sure it’s back to a safe level.

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