Connection Between Water Softeners and High Blood Pressure (2024)

Water softeners are devices attached to home plumbing systems that are designed to eliminate the problems that come from having “hard” water. This includes unpleasant odors/tastes, or stiff, scratchy clothes (after laundering).

Water softeners contain sodium to assist with filtration. The water shouldn't taste salty, but it can raise your blood pressure. Exactly how much sodium is in softened water depends on how hard the water is to start. Usually, the harder the water, the more sodium it will have once it passes through the filter.

This article takes a closer look at how water softeners work and why they contain sodium. It also explains how sodium in softened water may affect your blood pressure.

What Is Softened Water?

Hard water comes from certain types of wells, and the term “hard” refers to the fact that well water tends to have a rather large amount of dissolvedcalciumandmagnesium. Water softeners work by removing these substances, but to do so, they have to add a replacement. Commonly, that replacement is sodium.

In areas with very hard water, the softened water coming from your tap can actually add a significant amount of sodium to your diet. The harder the water, the more sodium the softening system must add to replace the dissolved calcium and magnesium.

How Much Sodium Is in Softened Water?

In order to figure out how much sodium your softener is adding, you’ll need to contact your local health department, who will be able to tell you the mineral content of your well. Ask for the hardness of your water in “grains per gallon.”

You can multiply this number by 8 to find out how much sodium (expressed in milligrams per liter) is added to your water by your water softener.

Does Salt in Water Softener Cause Hypertension?

Softened water typically contains about 12.5 milligrams (mg) of sodium per 8-ounce glass. If this water were graded according to the same scale the Food and Drug Administration uses for foods, it would be considered “very low sodium.”

If you live in an area with very hard water or tend to drink a lot of tap water, this extra sodium can start to add up. Studies have shown that following a low-sodium diet can lower yourblood pressure by about 8 mm Hg.

Some things you can do to combat sodium in your water include:

• Switching to a non-salt-based softening system
• Using bottled or filtered water (a simple pitcher filter will work) for cooking and drinking
• Having a plumber disconnect the cold water system from your softener so that only hot water (used for bathing and laundry) is softened

Though there are economical ways to eliminate this extra sodium from your diet, remember that the biggest sources of salt in the diet come from processed foods and the salt shaker.

Overall, it's probably okay to drink softened water every day. However, if you are on a medically low sodium diet, ask your healthcare provider to make sure.

Summary

Water softeners work by exchanging hard substances like calcium and magnesium for sodium. Generally, softened water contains about 12.5 mg of sodium per 8 oz glass, although the exact amount varies depending on how hard your water is. If you are on a low sodium diet, ask your healthcare provider if it is okay for you to drink softened water.

You can find this information by contacting your local health department and asking about the mineral content of your well. The Environmental Protection Agency (EPA) also offers a directory of state resources.

By Craig O. Weber, MD
Craig O. Weber, MD, is a board-certified occupational specialist who has practiced for over 36 years.