Pool TDS (How to Lower Total Dissolved Solids in Your Pool Water)

The pool water quality can be measured with the TDS level (Total Dissolved Solids). But how exactly is the TDS level tested and optimized in your pool water?

The TDS level is determined with a TDS water tester in ppm. The level should be between 1000 and 2000 ppm in the pool water. If the TDS level is over 2000 ppm, part of the water must be replaced to lower the TDS level.

This article will explain what the TDS level in your pool means and how to lower the TDS level.

What does the TDS level in the pool say?

Many substances and minerals get into your pool and are not filtered out.

This includes pool chemistry to lower and raise the pH level, algaecides, or cyanuric acid (chlorine stabilizer).

Bathers also carry various foreign substances into the pool water, such as residues of perfumes or sun creams, dander, salts, urine, and many other substances.

These colloidal substances do not degrade in pool water on their own and remain in your swimming pool even if the water evaporates.

The TDS level can be used to determine the total amount of dissolved substances and minerals in your pool water and, based on this, to determine the water quality.

In general, the following applies: The higher the determined conductivity of the water, the higher the measured level – increased levels are to be expected in saltwater.

In the next chapter, you will learn how to test the TDS level in a pool and, if necessary, reduce it.

Tip: The redox level (ORP) is also tested in your pool when testing the TDS level. You can find a detailed article about pool ORP in my blog via the link.

Measure the TDS level in the pool

You are asking yourself: How can a pool owner test the TDS in the pool?

The TDS in the pool water is determined with a special TDS meter in ppm (parts per million) or mg/l (milligrams per liter) – the TDS measuring device is often referred to as a conductivity meter.

The device for testing the pool TDS level works by measuring the electrical conductivity of all substances.

The collected data – the dissolved solids in the water – are then output as a total in ppm.

In addition to the electrical conductivity, the TDS meter also tests the electrical resistance of the dissolved particles in your pool water.

The result is the amount of dissolved particles in ppm or µS (microsiemens) – 2 µS/cm corresponds to 1 ppm or 1 mg/l.

How high should the total dissolved solids level be?

When is a TDS level ideal, and how high can the TDS level be in your pool?

You can read off the optimal levels ​​for water quality using the TDS level table.

TDS Level Water Quality
< 300 ppm Drinking Water
300 – 600 ppm Good
< 2000 ppm Okay
> 2000 ppm Bad

With a TDS level below 300 ppm, the water is ideally suited as drinking water – this level is typically not reached in a pool.

As long as the TDS level in your pool is below 2000 ppm, the pool water is considered harmless.

But the pool water should be optimized if the level is above 2000 ppm.

Extra tip: If your water tester shows mg/l instead of ppm, that’s no problem. 1 mg /l corresponds to the value of 1 ppm.

In my detailed article, you can learn everything about the different methods for testing pool water.

I will explain in the following text why you should lower the TDS level in your pool and how it works best.

How to lower the pool TDS level

Let’s summarize: The TDS level determines your pool’s water quality, and a TDS level above 2000 ppm is considered as bad.

But why is the pool water considered bad with a TDS level above 2000 ppm, and why does the level have to be reduced?

  • The total dissolved solids act as a blocker against the chemicals in the pool water.
  • Chlorine and other disinfectants decrease if the TDS level is too high.

Due to the points listed, if the TDS level is too high, beginners increase the disinfectant dose, leading to water quality problems and increased pool maintenance costs.

That’s why you have to lower the TDS level in your pool.

The easiest way to do this is by regularly changing the filling water.

But you can also try to filter out the proportion of dissolved substances in the pool water by using flocculants. How to use a flocculant in the pool is explained in my blog.

Follow my pool care instructions and make sure that you replace the filling water at regular intervals, then there should be no cloudiness in your pool.

Can a high pool TDS level be dangerous for humans?

It would be logical to assume that the sum of all dissolved substances in the pool poses a risk to the health of the bathers.

I can calm you down.

The WHO addressed the issue in the guidelines on drinking water and has not confirmed that health is endangered if the TDS level is too high. Source.

The reason for this statement is that no reliable studies exist.

But is the lack of a study reason enough to see something as harmless?

I’m not sure about that.

In addition, the document relates to drinking water and not to a more extended stay in your swimming pool.

Decide for yourself whether you want to continue swimming in a pool with a high TDS level.

For my part, I would prefer to keep the total dissolved solids in my pool below 2000 ppm and swim in the crystal clear pool water.

If your pool water is green and cloudy, you can use my search function to find other helpful articles on the blog to solve your problem.

Info: The drinking water with a TDS level that is too low is considered to taste bad. The same applies to drinking water with a too high value above 2000 µS.

Is it necessary to measure the TDS level in the swimming pool?

Many beginners get confused by special technical terms in pool maintenance, and sellers sell useless measuring devices and chemicals.

Does this also apply to the measurement of the TDS level in the pool?

Is it really necessary to constantly test the pool TDS?

  • When testing the pool TDS, only the electrical conductivity is determined and cannot be equated with a chemical analysis of the water quality.
  • Determining the quality of pool water with a TDS meter is a purely quantitative measurement that says nothing about the actual quality of the water.

If you want precise values ​​about the water balance, it is best to have the pool water tested in a laboratory or by an electric pool measurement device.

The measurement of the TDS level and the subsequent reduction can help with the pool maintenance, as total dissolved solids in your pool water act as a blocker of the pool chemistry.

However, it is not necessary to regularly test the TDS level in a private pool in most cases, but it cannot do any harm.

Info: I have to mention that a TDS water tester only takes into account electrically conductive substances.

Residues of pesticides, larvicides, and hormones do not conduct electricity and cannot be included in the calculations of the conductivity meter.

I hope you enjoy reading this article and share it with your friends!

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Hi. I'm Max Berg. I've been in the pool industry since 2015 and have always felt drawn to water. I'm the author behind swimfool.com, where I share my years of experience in pool maintenance and give helpful tips on keeping a swimming pool or hot tub clean. My tips reduce the costs of water treatment and protect the environment.

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