What Can I Do With My Hot Tub Water When It’s Time To Change It?

There's a great deal of attention on water conservation and smart water us, especially in areas of the country where rain or snowfall are below normal levels. Here are some tips to using your old spa water wisely.

The water in your hot tub can be recycled for use around your home, decreasing the amount of fresh water you have to pay for. It is critical to understand the proper uses for grey water and to know about any laws that may exist where you live. Many states and cities are beginning to encourage the use of grey water for limited purposes.

a Caldera hot tub sits with the power turned off getting ready to have the water recycled

In preparation for recycling your hot tub water, turn the spa off, let the water cool and let it sit with the cover off for at least 3 days after the last chemicals were added.

In some California cities where drought conditions are severe, communities are beginning to recycle all waste water and even turning waste water into drinking water. The City of Los Angeles has been recycling waste water for some time and seems to be leading the way. The Washington State Department of Health is also embracing grey water recycling.

Be sure to read up to understand all of the important nuances and safety measures when considering the recycling of grey water.

Image of a hot tub waterfall water feature close-up

Be sure to check with your local governing agencies to learn about any laws controlling the use of grey water.

Here are answers to some common questions when it comes to recycling hot tub water:

1. Is Recycled Hot Tub Water Considered the Same As Water from a Tap?

No. Spa water is classified as “grey water” or "sullage" similar to water from baths, showers and bathroom sinks. It is recyclable for limited purposes but it should never be used as drinking water or for washing dishes. Some hot tub water should not be used on plants unless it is tested and found to be free of chlorine and has a healthy pH balance. It is also important to check the local laws in your area.

a beautiful backyard with a couple in a Paradise Kauai Hot Tub Spa

Recycling hot tub water can reduce your use of fresh water and lessen the burden on your local water treatment and sewer system.

2. Can hot tub water be recycled?

Yes. Recycling grey water serves two purposes:

  • It can the reduce amount of fresh water needed for some household tasks.

  • It lessens the amount of water entering the waste treatment system.

a family enjoys some gardening with their energy efficient hot tub in the background

Salt water hot tub systems present a greater challenge for recycling hot tub water.

3. Can Water From All Hot Tubs Be Recycled?

Some hot tub models can use salt water systems that may damage lawns or shrubs, so it's not recommended for use on plants. In general you should not recycle the gray hot tub water for at least 3 days after you last added chemicals. Before you recycle spa water for any purposes you should check the local ordinances and laws in your area. If you live next to protected water lands, for instance, there could be unusual restrictions in your area about recycling gray water. Some communities outlaw it altogether so be sure to check the laws in your area.

table full of fresh vegetables demonstrates that you should not use grey water to water edible plants

Do not use recycled hot tub grey water for vegetables or other edible plants.

4. Does the Hot Tub Grey Water Need to Be Treated in Any Way Before It's Used?

There are some sacrifices to be made with hot tub water recycling. Most sources recommend waiting for three days after chemicals were last added to your hot tub, turning off the spa and allowing the water to cool. You certainly should not use your hot tub during this time. Chlorine should dissipate quickly, especially if you leave the cover off. After three days, test the water to make sure that the chlorine level is at zero. The pH should be between 7 and 8 to be safe for plants.

customer image of their hot tub at night with blue lighting and the waterfeature active

Use your hot tub grey water soon after draining or learn more about the safety concerns and procedures for storing grey water longer.

5. How Do I Get The Water From My Hot Tub To Where It's Needed?

Most portable hot tubs drain by gravity from a valve at the bottom of the spa that can connect to a garden hose. Using the hose, you can apply the water where it's needed directly, however, it only works if you're level with the hot tub or downhill from it. You can also use the hot tub drainage hose to send it to a storage container of some type. Depending on the size of your hot tub, finding the right storage container could be a challenge. You can always collect water to be recycled in buckets that are easily moved to areas of use. If you are going to store grey water over a few days then you will need a much more complex system of water storage.

You can also purchase an inexpensive submersible pump for $50 to $100 (make sure it connects to a garden hose where the water comes out or has an adapter). With it, you can pump water into storage barrels or apply it directly to the task at hand.

Image of a hot tub waterfall water feature close-up

Although recycled hot tub water has limited uses it will save some valuable water resources.

6. For How Long Can I Store Hot Tub Grey Water?

According to the website Greywateraction.org, grey water should not be stored for long periods of time without more complex storage conditions and treatment. Unless you are willing to become deeply educated on the subject, recycled grey water should not be allowed to sit for more than a few days. Grey water that sits without proper storage or conditioning turns into black water which can smell badly and be dangerous to your health.

7. What Are Some of the Best Uses for Recycled Hot Tub Water?

Recycled hot tub water can be used in a variety of creative ways, such as…

  • Water Some Plants (see point 4. above). Water the lawn, shrubs, ornamentals, flowers and trees. It's best to use it on well-established plants. Do not use it on edible plants.
  • Wash your car. Be sure to know the laws and regulations where you live. Communities near large bodies of water, rivers, coastal areas, protected marshes, etc. may have laws against allowing grey water to run into the sewers.
  • Wash off outdoor areas. (check the laws first) Wash your patio furniture, grill, lawn mower and other outdoor equipment.
  • Wash out your garbage cans.
  • Rinse down the patio and driveway.
  • Use it to flush toilets. Pouring it directly into the bowl rather than the tank.
  • Store it for later use. In proper grey water storage barrels or clean trash cans. Be sure to educate yourself before you consider storing grey water for longer than a few days.
Image of a hot tub on a beautiful modern style backyard at night

Hot tub grey water is never recommended for use in vegetable gardens or to water other edible plants or fruit trees.

8. Is It Safe to Use Recycled Spa Water on Vegetables and Other Edible Plants?

We do not recommend using your old hot tub water on your vegetable garden or any other edible plants.

9. Are There Restrictions Governing How I Recycle Grey water?

Potentially, yes. All recycled water uses are ultimately governed by local jurisdictions, and those take precedence over any of the above suggestions. Be sure to thoroughly research the laws in your area. Communities in coastal areas, near rivers, streams or lakes, and especially protected wetlands often have strict laws governing the use of grey water. The fines and damage to the ecology could be serious.

After using your hot tub water for months to treat tired muscles, relieve pain and help you rejuvenate, you can potentially get even more use from that water. And that makes your hot tub one the most efficient water users in your home.

The best high quality energy efficient hot tub cover helps to conserve water

A tight sealing energy efficient hot tub cover conserves water when your hot tub is not in use.

10. What Other Ways Can I Be More Water Conscious In Regards to My Hot Tub?

Another consideration for water conservation is to ensure that you have a high quality energy efficient hot tub cover. A hot tub cover does more than keep the heat in. It also protects your hot tub water from evaporation when your hot tub is not in use.


As we learn more and more about water conservation efforts, we'd like to hear how you're taking action. Are you already conserving or recycling water in your home? Would you make the effort to use recycled hot tub water for decorative plants that aren't getting enough moisture?

We're also very interested in what other uses you can think of for your recycled spa water. Please leave us a comment so others can take advantage of your ideas. Thank you!

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