Use Hot Tub Water to Water Your Garden Without Harming Your Plants

Since May is the beginning of the BIG gardening season in Seattle and the time when rain is less frequent, gardeners start to think about having to water their flowers and lawns. Yes, gardeners in the Northwest will have to pick up a hose and actually add water to their gardens.

Here’s a question posted on the Recycle This website that will be of interest to every hot tub owner:

“I want to use the water from my hot tub on the garden. It’s a great waste to just put it down the drain.  The water has chlorine in it.  Is there any way I can remove the chlorine from it to make it safe to water my garden?”

YES! Read on.

A few years ago when Seattle was in the middle of a drought, the City of Seattle Water Department called me to discuss using hot tub water to irrigate lawns and flowers (although not vegetable gardens). The topic came under the heading of  “gray” water- that is, water that has been used once and is no longer pristine.

The City of  Seattle is all in favor of using hot tub water to irrigate lawns and flowerbeds provided that gardeners follow our recommended method for draining safely:

CHLORINE

When you’re ready to drain, do not add chlorine for 1-2 days. Chlorine is very hard on plant life. However, it dissipates so quickly from a very hot hot tub (which is why you have to keep adding it!) that in a day or so there is no chlorine present in the tub.  Leave the lid open. Check chlorine levels with a test kit to make sure they are at zero. If they’re not, run the jets for 1-2 hours with the lid open and the chlorine will be gone.

pH

Plants in Seattle are accustomed to a slightly acid rain and tap water. If the hot tub water is too alkaline, plant life may suffer. Check to make sure that the hot tub water tests in the 7.2-7.4 range (neutral) before draining. If not, adjust the pH and run the jets to make sure any chemicals you’ve added are thoroughly mixed.

Switch to SilkBalance.

SilkBalance is made of all natural ingredients that do the job of balancing the water.  Use of SilkBalance will not harm flowers or lawns and pets can drink it with no ill effects. A hot tub that is treated with SilkBalance can be drained anytime you want to do it. No waiting until harmful chlorine is dissipated.

Follow the steps above to reuse your hot tub water safely for watering your lawn and plants.  Wherever you live, make sure it’s legal to use gray water on your garden plants. Check with your local municipality for any rules concerning hot tub draining and use of gray water.

SANUM PER AQUA. Latin for Health through Water.

4 responses to “Use Hot Tub Water to Water Your Garden Without Harming Your Plants

  1. This article is great. I would always advise people not to do this, but you’re right! Chlorine does dissipate quickly and plants are kind of used to low pH. Excellent!

    1. Matt:
      Thanks for weighing in. Changed your mind about using hot tub water to water your plants? It’s
      really a great thing to do to conserve water if your local jurisdiction allows it.
      Best wishes,
      Alice

  2. Everyone is talking about chlorine. That will easily dissipate in a few days. However, the question is that the spa water is high in alkalinity from the chemicals used in the hot tub which makes it more like salt water and at what alkalinity level is it safe to apply to plants?

    1. Good point you’ve made here, Ron.
      We advise getting the tub water to a pH of 7.2-7.4 before draining.
      Thanks for catching this.
      Alice

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