Harvesting Rainwater for Wooden Hot Tubs: A Simple Guide to Collect, Filter & Save

So, you’ve just purchased the wooden hot tub of your dreams—but now comes the expense of filling, running, and maintaining your new investment.

Good news: you can cut running costs without cutting corners. One of the easiest wins is harvesting rainwater for hot tub maintenance and refills.

What is harvested rainwater?

Rainwater harvesting means collecting rainfall for non-potable uses like irrigation and other outdoor tasks. Water can be stored in barrels, tanks, cisterns, or ponds for later use and, if needed, filtered and treated for more sensitive applications. It’s better for the environment and can lower your household water bills.

How to collect rainwater

Collect harvested rainwater in a water butt, via gutters, or even simple buckets, then store it for hot tub use. Since hot tubs are typically filled from a freshwater source (e.g., a hosepipe), substituting rainwater can save money and reduce demand on mains water. For more ownership prep, see what to know before owning a hot tub.

Why using harvested rainwater benefits wooden hot tubs

Rainwater is naturally soft and free of added chemicals, so you’ll typically need fewer chemical treatments to keep water clean. That’s kinder to the environment and helps protect wooden components from long-term exposure to harsh chemicals. You’ll also reduce your mains water use and monthly bills. For more eco ideas, explore our eco-friendly hot tub tips.

Does harvested rainwater need filtering?

Yes. Filter harvested rainwater to remove dirt, leaves, pollen, and debris before use in your hot tub. Depending on your local water characteristics, you may also wish to add a water softener or conditioner to balance pH.

How to harvest rainwater to use in your hot tub

To harvest effectively, install a catchment system with filters and, if required, pumps. Once collected, treat the water appropriately before filling the tub. If you’re planning power or drainage alongside your setup, review the basics in required garden connections for a hot tub.

This guide walks you through the steps to harvest rainwater safely and cost-effectively for your wooden hot tub:

Step 1: Install a rainwater collection system. Fit gutters, downspouts, and a storage solution (barrel or tank) to capture roof runoff for later use.

Step 2: Install a filter. Place a filter before the storage outlet or inline to remove debris before water reaches the hot tub.

Step 3: Install a pump. Use a pump (if needed) to transfer harvested water from the barrel/tank into your hot tub.

Step 4: Treat the water if necessary. Adjust with a softener or conditioner to bring pH into balance.

Step 5: Enjoy your hot tub! Once everything is set up, fill with harvested rainwater, then relax—while saving money and resources.

Rainwater harvesting is a smart way to lower bills and reduce chemical dependency. For long-term care tips and seasonal prep, see our hot tub ownership guide.

Is harvesting rainwater worth the initial investment?

While the initial setup can feel pricey, it often pays for itself by cutting water purchases and reducing chemical use. You also gain peace of mind knowing your soak water is clean and gentler on skin and wood components.