How to Raise the Alkalinity in a Hot Tub Without Chemicals

While a hot tub is an excellent place to relax, these appliances require careful maintenance of the water's pH level. Raising the alkalinity of the water will keep your tub water from becoming corrosive. Doing so naturally involves more work than using chemicals, yet can be accomplished by following some simple steps.

(Image: Jupiterimages/Comstock/Getty Images)

Things You'll Need

  • Water pH test strips

  • Distilled water

  • Tub cover

Raising the Alkalinity in a Hot Tub Without Chemicals

Step 1

Test your water regularly. You will find pH testing kits at any hot tub or pool supply store. The pH of the water, according to the Centers for Disease Control and Prevention, should read between 7.2 and 7.8. If the number is lower than this range, it is time to raise the alkalinity.

Step 2

Lower the water temperature. A high temperature reduces the solubility (ability to dissolve) of the naturally occurring mineral calcium carbonate. This can raise the acidity of hot tub water, according to the University of Michigan. By lowering the temperature of hot tub water from 105 degrees Fahrenheit to 94 degrees, for instance, you can reduce insoluble calcium carbonate by half, resulting in more alkaline water.

Step 3

Drain more often. If you're not going to use chemicals to treat the alkalinity of the water, an important way to increase alkalinity is by keeping the water fresh. Changing the water once a week--instead of once or twice a month--is effective in stopping calcium carbonate buildup that raises pH levels.

Step 4

Use distilled water. This is water that has been vaporized, condensed and collected in a form with far fewer minerals present. Although lugging gallon jugs of distilled water from the store to fill your hot tub is a little impractical, you can purchase a home water distillation system. While you can expect to pay $1,000 to $2,000 or more for a large model, it still may be a great investment if you are committed to keeping your hot tub free of chemicals.

Step 5

Cover your hot tub. This will keep particles from falling into the water that can lower alkalinity. If your hot tub is in the bathroom, common household cleaners such as toilet bowl cleaners contain high amounts of hydrochloric acid. Even a splash of acid landing in your tub will raise acidity and lower alkalinity.


High alkalinity can cause water to become cloudy, plug filtration systems, form mineral scales on the surface of the tub and even irritate the skin. It is essential to test your hot tub's pH level regularly.

References & Resources