Can You Fill a Hot Tub or Spa with Well Water?

Do you have a well sitting in your backyard? Maybe it crosses your mind if it’s possible to fill your hot tub with well water. So, is it possible and, if so, are there important things to know beforehand?

It is possible to fill your hot tub with well water. Millions of Americans use their wells daily to fill their hot tubs. But, because well water is completely natural, you will need to deal with dirt, minerals, and impurities when using it in your hot tub.

But, before diving into how to add well water, let’s look at the pros and cons of using well water in your hot tub.

Filling hot tub or spa with well water
Filling hot tub or spa with well water.

Is Well Water Safe to Use in a Hot Tub?

Well water is entirely safe to use in your hot tub. However, you will likely need to filter it before adding it. And then balance the chemistry to keep your spa or hot tub clean and running smoothly.

Water from a well is entirely pure, naturally filtering underground. But, this means it will carry minerals, metals, and dirt not typically found in treated water.

While swimming in well water is safe for swimmers, its contents can drastically affect the tub’s water chemistry and the hot tub itself.

Important Considerations Before Using Well Water in a Hot Tub

Even though you have this ‘free’ source of water in your backyard, there are essential factors to consider before filling your hot tub with well water.

Metals & Minerals

Untreated water contains metals and minerals, which can affect your hot tub. Even though this water is safe to swim in, minerals and metals can affect your hot tub’s integrity.

For instance, minerals such as calcium or magnesium can turn into scale deposits. Whereas metals, such as copper and iron, will stain the hot tub surfaces and bathing swimsuits, and discolor the water. If you have high iron in your water, quickly fix it with our handy guide, ‘How to Remove Iron from Pool Water (Water High with Iron).’

The high concentrations of metals and minerals in well water make it more challenging to balance the water chemistry than in regular tap water.

Well’s Flow Rate 

A well’s flow rate measures how many gallons of water can pump from the well in one minute. You’ll need to ensure that your well’s flow rate can handle filling your hot tub as often as you want/need to. You don’t want to run your well dry.

Experts recommend draining and refilling your hot tub’s water every three months, depending on usage.

Test Well Water First

Before deciding whether to use your well’s water for your hot tub or Jacuzzi, test it to know what kind of water you’re dealing with.

Testing it with both a metal test kit and a typical pool/hot tub chemistry test kit will give the best indication of whether your well water is suitable for hot tub use or not. And additionally, it will give you a better idea of what needs to be done to adjust the water.

For example, if you find the water is high in iron or other metals, you may want to filter the water first and then treat it with a metal sequestrant. The sequestrant will hold the metals in the water. This will prevent staining.

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Water Usage

An unexpected consideration is who else relies on the well for water supply. This is particularly important if your well has a low flow rate and if you share the well with neighbors. Check with them about using the water to fill your hot tub first.

Pros of Using Well Water for Hot Tubs

The primary benefit of using well water for your hot tub is that well water is free and unmetered.

The long-term savings of setting up your well and adjusting the well water will outweigh these costs. Especially if you live in an area with costly water bills.

Maintaining your well will set you back roughly $300-500 a year (depending on your area and setup), but well pumps have a lifespan of 8-15 years. So, a well-maintained well will save you water costs for your hot tub and your house.

Cons of Well Water for Hot Tubs

The major cons to using well water to fill your hot tub are having to deal with trace metals and minerals and the potential of running your well dry.

High concentrations of metals stain and discolor the hot tub water and affect water clarity. Whereas, minerals can create scale deposits that may cause costly damage to the inner hot tub mechanics, such as the pipes and heater.

Depending on the size of your well and flow rate, it can be time-consuming to fill it up.

And, the costs of balancing your water chemistry can be expensive. You’ll also need to spend some time doing this. A larger hot tub is going to cost more time and money to fill with well water.

How to Fill a Hot Tub Using Well Water

Follow these steps to ensure you have the best setup for filling your hot tub with well water.

1. Check Well’s Flow Rate

Before starting anything, you’ll need to ensure your well’s flow rate is strong enough and fast enough. The speed of flow rate your hot tub needs depends on the size of it and what additional features it has.

A typical hot tub takes about 30-45 minutes to fill up, but it can differ when using a well as the source water.

Measure the flow rate by seeing how many gallons of well water you can collect in a minute. To do this, just fill a 5-gallon (19 L) bucket keeping track of the number of times you filled the bucket. Then add these numbers together for an approximate flow rate.

Now you can calculate how long it will take to fill your tub. Just take the hot tub’s volume and divide it by the flow rate and you’ll have the number of minutes it will take to fill.

e.g. if your well supplies 5 gallons (19 L) per minute (gpm) and your hot tub is 1000 gallons (3,785 L) the formula would be:
1000 (hot tub volume) / 5 (flow rate) = 200 minutes

2. Test the Water

Before filling the hot tub, the next step is to test the well water for metals and chemical composition.

Luckily, this isn’t a hard process, only requiring you to take a sample of well water. Use a metal test kit to test the water sample for metal concentrations. And use a pool chemistry test kit to learn the water’s chemical composition.

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Once you know where you stand, you can better decide whether using your well’s water for your hot tub is a good idea.

3. Attach the Hose

Once you complete the above steps, you can attach one end to the tap closest to the well’s pump.

With the other hose end, attach a prefilter, which will help filter out metals and minerals. This prefilter lessens the challenge of balancing the water afterward. Once you connect it, place this hose end into the hot tub.

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4. Turn On Well Pump

With all hot tub equipment turned off, turn on the well pump and begin filling your hot tub. Depending on your well’s flow rate and hot tub size, it may only take 30-45 minutes.

If your flow rate isn’t good, it may take hours to fill up the tub. Make sure to give the pump a break every so often.

5. Balance Water Chemistry

Now that your hot tub is full of well water make sure to retest it to check for metals and water chemistry. Then, hopefully, the prefilter has done its job, and balancing everything will be much easier.

Make sure not to add chemicals all at once, no matter how tempting. But, if you’re unsure what order is best to add chemicals, check out our guide ‘What Order Should You Add Pool Chemicals? (Answered!)‘.

Can You Burn Out a Well Pump Filling a Hot Tub?

It is doubtful you will burn out your well’s pump filling your hot tub. But it will depend on your well’s flow rate and hot tub size.

The flow rate is the biggest deciding factor on how hard your well’s pump runs. If you notice the water flow is low, and it’s slow to fill your hot tub (an hour or more), give the pump regular breaks.

To avoid burning the pump out, turn off the pump for an hour every hour. This will help keep the pump from overheating and wearing out quickly.

In addition, if there is a risk of the well running dry, you need to monitor the water level carefully. Running a well pump dry is a common reason for burning out the pump.

Can Filling a Hot Tub Run Your Well Dry?

It is extremely unlikely you will run your well dry filling your hot tub.

Because you only need to fill up your hot tub 3 or 4 times a year, it shouldn’t run your well dry. Most wells are incredibly deep and have enough time between each heavy usage to recover.

If you are nervous, you can check your recovery rate. And keep an eye on the well’s water level, if possible, to see the recovery rate.

Wooden outdoor hot tub filled with water
A wooden outdoor hot tub filled with water.

Final Thoughts

If you have a well, you can stretch your water-saving costs further with your hot tub.

Using well water requires extra care and chemistry balancing, but the long-term cost benefits far outweigh the challenge.

Related Reading:
How Long Does It Take to Heat a Hot Tub? (and Tips for Faster Heating)
How to Shock a Hot Tub
2 Ways to Raise pH in Hot Tub (pH is Low)
Do You Need to Shock Hot Tubs?
How to Lower Hot Tub pH Naturally (Using Vinegar)
How to Raise Alkalinity in Hot Tub (Alkalinity is Low)
Soda Ash vs. Baking Soda for Hot Tub: Which is Better?

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