How Water Hardness Affects Your Hot Tub, House & Health

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Hard water contains deposits called scale, which build-up on hot tub equipment causing premature failure and clogged plumbing if left unchecked. But, did you know that hard water can also be damaging to your skin? Learn how to perform a water hardness test to safeguard your hot tub, house and your skin here.

Hard Water vs. Soft Water

Many people ask, “What is hard water?” In layman’s terms, it is water that contains a high concentration of dissolved minerals, primarily calcium.


When hard water is heated, the minerals form “scale” and cling to pipes & other surfaces. This is what causes water marks on glass, a rust ring in the toilet bowl, and a scum line in your bath or hot tub.

Scale buildup also prevents efficient heat transfer, causing your water heater or hot tub heating element to have to use a lot more energy to heat the water. Soft water contains low amounts of minerals. It can be naturally occurring, or produced with water treatment devices that remove hardness elements, such as calcium and magnesium.

Effects of Hard Water on Skin

According to Virginia Tech, 85% of U.S. water is hard – meaning that it contains high levels of calcium carbonate, magnesium hydroxide, calcium sulfate, or other trace minerals. Though hard drinking water is generally not harmful to your health, bathing in it can cause some problems:


  • Itchiness
  • Acne
  • Skin & Hair Dryness
  • Flaking
  • Dullness
  • Dry hair

The high mineral content in hard water prevents it from reacting properly with soap. Instead of triggering lather, hard water creates a soap scum layer on the skin. This not only clogs pores, but also causes irritation.

Is Hard Water Causing your Acne?

After washing your face with hard water, impurities and minerals remain on your skin. When your face cream comes in contact with these impurities, they bond together and clog pores, causing acne. Research has found that calcium and magnesium tend to cause most hard water related breakouts.

Hard Water linked to Free Radicals

In severe cases, some elements in hard water can act as free radicals, even breaking down the collagen in healthy skin cells, allowing skin to be much more susceptible to sun damage. A common component of hard water, iron, is said to be one of the most detrimental elements. Iron deposits on skin get energized by the sun, which has been linked to some cases of skin cancer.

Hard Water & Eczema

Research has found a correlation between some skin disorders, like eczema, and hard water. “Minerals, such as calcium, that are found in high concentration may cause loss of moisture in the skin, which can lead to irritating conditions, such as eczema.” Says New York dermatologist Dr. Eric Schweiger.

face care

Use Distilled Water

To help prevent the irritation and other effects of hard water, wash your face with distilled water. Note: Many bottled water brands have high mineral content (for better taste), use your water hardness test (Hardness Test Strips) to determine if your bottled water is suitable.

hard water hair

“Hard Water Hair”

Hard water causes hair to become dry and straw-like, creating a tangled mess and painful combing experience. Washing your hair in hard water, along with soaking or swimming in chlorine is a recipe for hair damage. To avoid this, try using a hard water shower head filter & pinning your hair up before entering the hot tub. A natural hair conditioner will also help combat hair dryness and restore shine.

cleaning your glass

Household Cleaning with Hard Water

You may have noticed water spots on your cooking dishes and drinking glasses or even soap scum in your bathtub that you just can’t seem to get rid of. These are not signs of bad housekeeping; these are results of hard water!

How to Clean and Remove Hard Water Stains

Hard water makes cleaning even more of a chore because of its anti-social behavior with your cleaning products. Because of this, most people believe that they need to use synthetic detergents to get things clean. However, I have a simple, earth friendly and money saving solution to creating your own hard water stain remover:

  1. Fill an empty spray bottle half full of white vinegar.
  2. Fill the remainder with water.
  3. Spray vinegar solution onto your shower doors, tub, tile, and sink.
  4. Use a sponge or rag to wipe away scum on doors, or a nylon bristle brush to clean the toilet bowl.

cleaning supplies

If you need a little more cleaning oomph, you can mix white vinegar and baking soda to create a paste. Apply paste to surface, wait 15 minutes and scrub away, then rinse the area. Towel drying your cleaned surfaces is important if you don’t want to leave behind water marks. NOTE: Never use abrasives on acrylic. This will cause a scratched and dull surface appearance.

Cleaning Your Hot Tub & Acrylic Surfaces

Acrylic surfaces, like your hot tub shell, are susceptible to scratching and dulling if cleaned with abrasive tools or cleaners. A gentle cleaner like CleanAll and a soft sponge will remove hard water stains without causing damage.

Preventing Hard Water Scale

Hard water scale build-up is easily preventable with the use of a hose-end pre-filter, a device that attaches to the end of your house and filters the water prior to it entering your spa.

Do You Have Hard Water?

Test Strips

A water hardness test kit is the easiest way to determine if you should be concerned with hard water. Hardness Test Strips are easy to use, inexpensive and take seconds to return results.

Have a question about hard water? Post a comment below!


  1. I””m amazed at the amount of information offered on the Spa Depot website without the pressure to buy, buy, buy. I””ve spoken on the phone with consultants about well water for spa health and chemical balance issues and they””ve been very helpful. I””ve had three orders received within 3 days. Thanks for the great service and answers. I don””t know who started the company, but kudos to you cause your good work trickles down through your company like smooth, cool water from a rocky outcrop to a fern filled pool. Lovin”” it. Thanks.


  2. This is very informative; thank you! After my first spa fill last September, I purchased the Pre-Fresh attachment. The difference really was easy to see. Our second fill in mid-December stayed usable until this past weekend. (In our frigid New England winter that”s important; it”s not practical or safe to change the water in February or March!)


  3. Thank you for your comment, Matt. Great tip about draining and refilling in the middle of winter. I bet you”re excited for the warmer weather, I know I am!


  4. Do you mind if I quote a few of your posts as long as I provide credit and sources back to your webpage? My blog is in the exact same niche as yours and my users would really benefit from a lot of the information you provide here. Please let me know if this okay with you. Many thanks!


  5. Hi Patricia, Yes, that would be ok. Thank you for asking! Please let me know if you need any additional information. Thank you, Kaisa The Spa Depot


  6. what can i put in my spa when filling it up? I have hard water and want to keep my jets in spa from so much calcium.


  7. Wish I had found you 4 years ago. I am afraid that my spa is ruined. I have a mess with leaks that I am trying to fix. We have well water and I have a gritty scale inside the tub. What can I use to clean this off?


  8. Hi Tonya, As long as you don”t have too many leaks, your spa isn”t ruined. Most leaks are small, and even for some bigger leaks we have a couple of products that can come in very handy! Our Seal-a-Leak works well for small leaks, and Plast-Aid work great for small to medium leaks you can reach. You can find them on these two pages – Our Spa System Flush can help loosen up some of the scaling on the walls of your spa. Here is the link to that page – Once you”ve used the System Flush and cleaned the side walls, when you refill the tub it would be a very good idea to use our Metal Free to prevent the build up from happening again. Here is a link to the Metal Free – If you have any other questions, feel free to call our tech department at 800-823-3638. Thank you! Mark The Spa Depot


  9. Ok so I have tried the Seal A Leak. I have leaks underneath. Guess it is time to call someone. So frustrated. I have had no one to help me/educate me regarding the care of our spa. I so wish I had found this site 4 years ago.


  10. Hi Tonya, Sorry to hear you’re still having troubles with your spa. We understand your frustration and are glad you were able to find our site. You may find it useful to give our tech department a call, and one of our team members can help you trouble-shoot your leak problem. Our technicians are available Monday – Friday 8am-5pm Pacific: 800-823-3638 Thanks, Bonni The Spa Depot


  11. There””s certainly a great deal to learn about this issue. I love all the points you””ve made.


  12. Hey, I”m here for the first time. I came across this article and found it truly useful & it helped me out a lot.


  13. Liver locations, freckles, wrinkles and other blemishes and skin discolorations are brought about by excessive sun also.


  14. I absolutely loved every little bit of it. I have you book marked to check out new things you post…


  15. Hi Nancy, Great question! To clean the inside of your hot tubs plumbing system you should use Spa System Flush, this will help remove build up and deposits. Also, to prevent future build up try using the Prefresh Water Fill Filter when filling your spa. Please let me know if there is anything else I can help you with! Thank you, Bonni The Spa Depot


  16. We have a chalky, white buildup around the top of the water line and nothing seems to remove it. What do you think we should do?


  17. Hi Jerry,
    Thank you for posting! I am happy to help.
    The chalky white build-up is excess calcium in your water. The best way to remove the build-up from the waterline is to use a little bit of Spa System Flush on a damp rag:
    To prevent calcium build-up in the future you can use a Pre-Fresh hose-end filter, which will filter out excess calcium and minerals before it enters your spa:
    I hope this is helpful. Please let me know if you have any additional questions.
    Thank you,


  18. Is there any thing I can add to my Hot Tub to decrease the hardness and clean the element ? Hard water has built up and its becoming harder to heat up ?
    ie: Muriatic Acid ???


  19. Hi Gary,
    To remove all that scale build-up, clear your pipes and heater element with Spa System Flush and drain the water. When you refill, use a PreFresh hose-end filter to cut down on the amount of calcium in your tub, and use a weekly scale treatment like Spa Defense to keep the calcium in your water from forming.
    Spa System Flush should be added every time before you drain and refill to dissolve built up calcium deposits since you have very hard water.
    Adding muriatic acid would cause your pH to drop, and could cause damage to the tub.
    Spa System Flush:
    PreFresh filter:
    Spa Defense:
    Let me know if you have any further questions.

    Liked by 1 person

  20. So when I fill my spa in the spring should I turn off my water softener or fill it with it on? Fighting major calcium residue on spa , and can adding vinegar clear it up ?


  21. Hi Gary,
    Try filling the spa half or three-quarters full of softened water, and the rest of the way with regular water. The only thing vinegar is going to do is decrease the pH, so unless your water has high pH or TA, save the vinegar for fish and chips.


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