How to Test Hot Tub Water Quickly and Accurately Every Time

Michael Keenan


Hot Tub Water Chemistry

Keeping a check on the chemical levels in your hot tub water is essential for the upkeep of your equipment and the health and well-being of the hot tub users. Almost every hot tub maintenance action will start with water testing.

It’s important to learn how to do this quickly and accurately.

Testing the water may seem daunting at first, but with the help of this article, you’ll learn how to do it quickly and accurately! Find out why testing is important, what chemicals should be balanced, which testing methods are available and more!

Let’s take a look at how to test your hot tub water properly and get it right every time.

how to test hot tub water

Quick Answer:

Testing your hot tub’s water is essential to keep it running smoothly and avoid any health issues. You can use test strips or liquid test kits at home, or take a sample to a professional for more accurate readings. Checking your chemical levels every week ensures that your hot tub remains clean and safe.

Why Should You Test Your Hot Tub Water

The temperature of your hot tub is usually set between 102 and 104 degrees Fahrenheit (38-40 C). If you don’t keep an eye on the chemical composition of your hot tub water, this temperature makes it an ideal breeding ground for bacteria and other disease-causing organisms.

NW Direct Pool and Spa Test Strips - 100 Strip Pack
THE ULTIMATE AT HOME POOL TEST STRIPS for your swimming pool & spa. Tests for 6 parameters: total hardness, total chlorine, bromine, free chlorine, pH & total alkalinity

If you don’t test your hot tub water regularly it can cause rashes, skin infections and urinary tract infections. Too much of a certain mineral and too little of some can cause damage to your pumps, filters and heating equipment too!

Regular testing will help you keep water quality problems in check. Most water quality issues are due to chemical imbalance of some kind – things like white flakes in your spa and green hot tub water. I explain in detail how to fix these issues.

Ideal Chemical Composition of Hot Tub Water

The most important chemical compositions that you should keep an eye on include pH, total alkalinity and calcium hardness.

The ideal water chemistry in your hot tub should be as follows:

  • Bromine Level: 3.00 to 5.00 parts per million (ppm)
  • Chlorine Level: 1.00 to 3.00 ppm
  • Total Alkalinity Level: 80 to 120 ppm
  • pH level: 7.4 to 7.6
  • Calcium Hardness: 100 to 150 ppm

How Often Should You Test Your Spa Water

You should check your hot tub water every week to make sure that all the chemicals are balanced. This will ensure that your tub remains neat and clean. Maintaining the chemical balance is important to keep the tub working and to prevent health issues.

Cloudy hot tub water – how to fix it! Have a look at that article to see what I mean.

Prevention is always better than spending loads of money on repairs and replacements. Set a reminder on your phone so that you don’t forget your weekly chemistry check!

balanced hot tub water

Hot Tub Water Testing Methods

The three common methods to test your hot tub water include:

  • Test strips
  • Liquid test kits
  • Getting water samples checked professionally

You can use test strips and liquid test kits by yourself with a little care. But if you need a professional opinion, you can always take a sample to your local pool or hot tub dealer and check out the chemical composition.

Did you know you can maintain a hot tub without using harmful chemicals – or at least reduce your chemical use? See my guide now!

Let’s take a detailed look at how to test your hot tub water.

How to Use Test Strips

Test strips are one of the easiest methods to keep a quick check on your hot tub water. They are super easy to use and give you quick results. This method is ideal if your hot tub water looks and feels clean and you just want a quick check of the chemical composition.

Basic test strips check for chlorine / bromine, pH and alkalinity.

Leisure Time Test Strips for Spas and Hot Tubs
Helps measure the chemicals in your spa water; tests for pH, alkalinity, calcium hardness, and chlorine

How to Take a Reading

Keep the water circulating and collect a water sample in a clean container. Make sure you take the water sample as close to the middle of the tub as you can.

Dip the test strip in the container of sample water collected. Wait for about 15 seconds or for as long as the instructions on the packaging ask you to.

Check out the color swatches on the strip to the color swatches on the bottle to check out if your chemical levels are balanced or not.

Tips to Get Accurate Readings

  • Always make sure that you use fresh strips as expired strips can give you wrong readings.
  • Store your test strips in proper containers. Keep them indoors and away from direct sunlight.
  • Make sure that your hands are clean and dry. Wet fingers can contaminate the strips that you haven’t used.
liquid water test kit

How to Use Liquid Test Kits

Liquid test kits take a little more time than test strips and the better kits might be a little more expensive. But some people find these results easier to read than trying to read the tiny color swatches on the test strip.

Basic liquid tests only check chlorine and pH levels, but there are liquid tests that give you total alkalinity, calcium hardness and chlorine stabilizer readings as well.

Poolmaster Essential Collection Chemistry Case 5-Way Swimming Pool & Spa Water Test Kit
For maintaining proper water chemistry; Tests for Chlorine, Bromine, pH, Acid Demand, and Total Alkalinity

How to Take a Reading

Following package instructions is the first and most important tip.

These kits come with testing containers. Collect water samples from your hot tub in these test containers.

Add the reagent drops to the collected samples and wait for the specified time. Add indicator drops to this solution and wait for the color change.

Compare the color of the liquid to colors in the information booklet provided with the kit to find out the chemical composition.

Tips to Get Accurate Readings

  • Use fresh reagents that are not expired.
  • Do not store the test kit in highly humid or extremely hot areas.

Travel Story!

During our travels in Bali and Thailand we stayed in a few managed holiday lets. Most had their own Pool Guy. I was amazed that they tested the hot tub and pool water every day! Definitely overkill. But I guess the owners didn’t want to take any chances with clients getting sick due to the water chemistry being off.

Get It Checked Professionally

While it is good to test your hot tub water regularly using test strips or liquid test kits, these home tests are not a long term solution. If you want to keep your hot tub running smoothly you might consider getting your chemical levels checked out by professionals at least a couple of times in a season.

To save some money you can take a water sample to your local hot tub or pool dealer and run a battery of tests to ensure that everything is as it should be. Alternatively you can find a local professional to come out and do the testing.

Tips for Collecting the Spa Water Sample

  • Use a clean container to collect the sample. Keep this container aside and don’t use it for anything else.
  • Collect water from the middle of a circulating tub.
  • Close the container properly and take it to your hot tub dealer immediately. Having the sample sitting around – especially in direct sunlight or high temperature – can give inaccurate readings.


What are signs that the hot tub water needs to be tested?

Signs that the hot tub water needs to be tested include foam, cloudy water, and unpleasant odors in the water.

Are there any other methods to quickly and accurately test a hot tub’s water quality?

Yes, there are other methods such as digital testers, colorimetric strips and automated testing systems that can quickly and accurately test a hot tub’s water quality with minimal effort from the user.

Can you test hot tub water for bacteria?

Yes, you can test hot tub water for bacteria. Some home testing kits on sale can test for bacteria but it is better to have a professional do this in my opinion.

What type of illnesses can result from bacterial growth in hot tub water?

Illnesses such as skin infections, eye and ear problems, and urinary tract infections can result from bacterial growth in hot tub water.

How long after shocking a hot tub can you test the water?

If a chlorine shock is used, it is best to wait 24 hours after shocking the hot tub before testing the water. For non-chlorine shock, wait 15-20 minutes. That allows enough time for the chlorine levels and other chemicals in the hot tub to stabilize, so that you can receive an accurate reading.

Parting Words

A visibly clean hot tub might not always be as clean as you think. It is important to regularly test your hot tub water right from the day you get your hot tub installed.

Perfectly balanced water in your hot tub will prolong the life of your hot tub equipment and prevent any illnesses as a result of bacterial growth. Get into the habit of checking your hot tub water regularly to avoid major repairs and maintenance in the future.

Test strips and liquid test kits are great for a quick check, but nothing beats getting it checked professionally!

Don’t forget to use fresh test strips or reagents when testing your spa water to ensure accurate readings! Additionally, store your test kits away from high humidity or heat so they don’t get spoiled over time – easy peasy!

Now you know how to test hot tub water properly – what are you waiting for?

Last update on 2024-07-20 / Affiliate links / Images from Amazon Product Advertising API

michael keenan author

Author - Michael Keenan

I'm Michael Keenan the owner and creator of the Outdoor Care Guide. I'm a trained horticulturist with over 30 years of experience in pool care, plant care, and landscape care! Seemed like a good idea to share - I think I can make your life easier and save you some time and money!