Filling a hot tub with well water can cause several potential complications. Fortunately, there are some simple steps that you can take to avoid these potential issues. Today, we will explore a few things that you should know before you fill your hot tub with well water.

Should You Fill A Hot Tub With Well Water?

So if well water can cause issues with your hot tub, is it even a good idea to use it? While you could truck in water to fill your hot tub, the expense of this is usually more than the cost of properly treating the well water. Since you will also need to periodically top up your hot tub as water is lost to evaporation and splashing, you’ll need to use well water anyway. In our experience, it is almost always more economical to simply properly treat the well water in your hot tub.

What Problems Can Well Water Introduce To A Hot Tub?

Calcium Hardness

One of the most common issues with well water is high calcium hardness. Water with high calcium hardness can often look a little hazy and if left untreated will cause scale buildup on key components of the hot tub like the heater and jets.

Scale buildup on your heater is especially problematic as it greatly reduces its efficiency. This means that the heater will need to run for longer to keep the water at your desired temperature, leading to higher energy bills. Scale buildup on other components with moving parts will cause added friction in those moving parts, leading to an increase in wear and tear and a shorter lifespan.


Another common problem with well water in hot tubs is unbalanced alkalinity. Depending on where you live, the alkalinity in your well water can be very low (acidic) or very high (basic).

Water with high alkalinity causes similar problems to water with high calcium hardness (haziness and scale buildup) and can make high calcium issues even worse. Water with alkalinity, on the other hand, can mask potential calcium hardness issues by making the water appear crystal clear, even when there are other issues. Since water with low alkalinity is acidic, over time it can also cause damage to other key components of the hot tub, especially those made of metal (like the heater element) or rubber (like the seals in the pumps).


Total dissolved solids (TDS for short) is a measurement of how many minerals, metals and other inorganic matter is present in water. Water can only hold a certain amount of solids in suspension. The more dissolved solids that are present in the water, the less “room” there is for chemicals to properly incorporate into the water. High TDS, therefore, can reduce the effectiveness of the chemicals that you add to the water. This means that you will need to add more chemicals to the water in order to keep the water clear and balanced.


Some well water can have metals like copper and iron dissolved in it. On their own these metals are typically pretty harmless, though they will react when the hot tub water is shocked. If there are enough metals present in the water, the water will either turn to a rusty colour when the water is shocked or cause staining on the surface of the hot tub.

How To Treat Well Water In Hot Tubs

So now that we know a little about all the things that can go wrong with well water, how can we treat well water for use in a hot tub?

If you plan on using well water in your hot tub, we recommend bringing in a sample of your water in for testing before filling it. This will allow your local hot tub retailer to properly diagnose potential issues and help you treat them before they become an issue. Based on the results of this test, you can apply the following fixes.

  • If your well water has high calcium hardness we recommend filling your hot tub with softened water, if possible. You can then add in some calcium increaser to bring the calcium hardness level to the recommended level. If adding softened water isn’t an option, you can add in a weekly dose of scale preventer to keep the calcium from combining and causing scale buildup.
  • If your alkalinity is low, you can simply add in some alkalinity increaser after filling the hot tub (once the water has reached its set temperature).
  • If your alkalinity is high, you’ll need to slowly add in some pH decreaser over the course of a few days to slowly bring it down to the recommended level (your hot tub retailer can give you exact measurements).
  • Unfortunately, if your TDS is high there’s not much you can do. Our best advice would be to simply drain and refill the hot tub a little more frequently than you normally might.
  • If your well water contains metals we recommend using a specialized filter that is designed to filter out common metals like iron and copper that can cause issues with hot tubs. These filters are fairly inexpensive and can be bought at your local hot tub retailer. Simply screw it onto the end of your garden hose as you fill it to remove the metals before they even reach your hot tub!

Key Takeaways

  • In almost all cases, well water is completely fine to use in your hot tub. As long as you regularly test and balance your water, you should have no issues with either water quality or comfort.
  • If not properly treated, however, well water can cause water quality issues in hot tubs and can even lead to a lower lifespan for many different components of your hot tub.
  • Before you fill your got tub for the first time, bring in a sample of your well water to your local hot tub retailer for testing. This will give you an idea of what you’re up against, and how best to treat the water in your hot tub.
    With the exception of high TDS, every potential problem with well water can be fixed with either balancing chemicals or relatively inexpensive accessories.

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