The Negative Effects of Hard Water in a Hot Tub


Dealing with hard water in a hot tub can be a huge burden. Not only does it wear on your equipment, but it also leaves you with symptoms on your skin and in your hair that can make the prospect of taking a dip in your hot tub a less than appealing one.

Hard water can lead to problems in your hot tub itself: there can be scale deposits that feel like sand paper on your skin or mark the acrylic, you can get significant build-up in your plumbing, and it can cause your heaters/pumps to fail prematurely. While you may be familiar with some of the negative effects on your equipment, how about what your body goes through when the hot tub water is mineral rich?

What is hard water?

Hard water is classified as such when water content has a high concentration of naturally occurring dissolved minerals. The most common minerals that accumulate in water are calcium and magnesium. When the water is heated, the minerals begin to form scale and cling to pipes and other surfaces. This is what causes watermarks on glass, rust in your toilet, and build-up along the waterline in a bath or hot tub.

What’s wrong with scale?

Aside from being visually displeasing and harmful to your skin, it prevents efficient heat transfer which means your water heater or hot tub heating element expends more energy to heat your water. The decrease in efficiency will mean you’re paying more to heat your water and are most likely going to need a new heater before you normally would need to.

The Harmful Effects on Skin

Most of the water in the US can be clarified as “hard water.” Only about 15% of the water in the country can be categorized as naturally “soft,” according to a study conducted by Virginia Tech. Although high concentrations of dissolved minerals are okay to drink, it’s tough on your skin. Minerals like calcium carbonate and sulfate, magnesium, and other trace minerals are the most detriment to skin, creating symptoms like dryness, itchiness, clogged pores, and dullness.

One reason hard water is tricky is because it doesn’t react properly with soap. Instead of lathering on your skin, hard water creates a scummy layer on the skin that clogs the pores and results in irritation instead of leaving it clean.


Hard water can be a contributing factor to chronic conditions like eczema. High concentrations of calcium in water can rob kin of moisture and can make itch and become irritated, often in a cyclical fashion that is common in eczema sufferers.


After soaking in hard water (or washing your face, for that matter), some minerals are too small to be washed away so they settle into your pores. If you get out of the hot tub that is filled with hard water and put on lotion to try and remedy dry skin, all you’re doing is sealing your pores which often leads to acne outbreaks. The calcium and magnesium in hard water are the most likely culprits that cause hard water-related acne.

Free Radicals

If you’ve ever watched a beauty commercial, you may have heard the term “free radicals.” In some severe cases, elements in hard water can act as free radicals which break down the collagen in otherwise healthy skin cells. This makes skin more susceptible to sun damage and skin cancer, particularly if there’s a high iron content in your hot tub hard water.


In addition to skin, hard water can be very detrimental to the condition of your hair, particularly if you’re letting it soak in it. Hard water strips valuable moisture and natural oils from the stand of hair which results in breakage and unnecessary damage, particularly in bleached or treated hair.

If your hot tub has a serious hard water problem, you may need to clean the system and start over. All you have to do is Google a map of the US and the average hardness of your water to know whether your fill water is a major problem.

    • Use a system flush to clean your equipment before doing a standard hot tub draining.

    • Clean your hot tub acrylic with a soft cloth and gentle cleaner that isn’t abrasive to the acrylic as it can be easily scratched or dulled if the wrong products are used.

    • Refill the water using a pre-filter—this will help your water start off without so many dissolved minerals plaguing the system.

    • REMEMBER—you need some minerals in the water, otherwise your water becomes caustic and will strip your equipment.

How do I know if I have a harder hardness problem?

You should be regularly testing your hot tub water with something like a test strip kit. They are easy and inexpensive and take little time to return results.

You should be keeping the water between 200-400 ppm, depending on the finish of your hot tub. You can get chemicals to either raise or lower at number if it fluctuates.

Other symptoms of a high mineral content in water include cloudy water, scale formation around the water line, and a hot tub surface that feels like sandpaper to the touch. The latter usually occurs when hard water mixes with water that has a high pH balance. Make sure you keep the pH, alkalinity, total hardness, and sanitizer levels all balanced to make sure your water feels good to you and doesn’t cause any undue side effects.
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