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TDS In Water: What It Is & How to Calculate

Scott Winfield
Written by Scott Winfield
Last Updated on

Wondering about Total Dissolved Solids (TDS) in your water? It’s a common concern, as TDS are found at varying levels in all US water supplies and can affect your water’s taste and quality.


Our guide simplifies TDS for you. We answer what TDS is, how to measure it, and how to reduce TDS in water. We also explore the health effects of drinking water with high levels of TDS, how it gets into water supplies, and much more!

What Is TDS in Water?

TDS in Water
TDS in Water

TDS stands for Total Dissolved Solids. It measures the total amount of dissolved solids, like minerals, salts, and metals in water. For example, if you have a water pitcher with one mg/L TDS, there is one milligram of TDS in each liter of water. 

When calculating TDS, all of the dissolved solids in the water are measured as one. The measurement doesn’t distinguish between the different types of solids. For example, if lead, calcium, and magnesium are present in the water, this will all be recorded as TDS.

How Does TDS Get in Water?

There are three main ways TDS can get into your water:

  • Plumbing: Old pipes can leach metals or other materials into your water supply.
  • Natural sources: Minerals and salts can dissolve into groundwater from soil, rocks, and springs.
  • Treatment processes: TDS can enter your water supply from chemicals used to treat and disinfect water. 

For example, most US cities and towns treat their water with disinfectants like chlorine to kill bacteria and other harmful organisms.

Of course, this means it’s fairly common for there to be high levels of these chemicals in your drinking water. Chlorine makes tap water taste and smell great, but it can react with certain organic compounds to form substances like trihalomethanes (THMs).

Consuming large amounts of chlorine is unhealthy, and it’s also been linked to many serious health problems, including cancer and congenital disabilities.

If you use a water pitcher and you notice a lot of white sediment or foam in the storage tank, there’s probably a high volume of chlorine or chloramine in your tap water.

List of Organic & Inorganic Total Dissolved Solids in Water

The following is a list of organic and inorganic total dissolved solids in water, organized by type.


  • Carbonates
  • Bicarbonates
  • Organic acids
  • Amino acids
  • Proteins
  • Sugars
  • Urea


  • Calcium
  • Magnesium
  • Sodium
  • Potassium
  • Chloride
  • Sulfate
  • Phosphate
  • Carbon dioxide

While all water contains dissolved solids, the levels of these solids vary depending on the source. For example, groundwater typically has higher levels of dissolved minerals, while surface water from rivers and lakes tends to have lower levels.

Water that has been treated with a reverse osmosis system also typically has very low levels of dissolved solids.

Normal TDS of Drinking Water in PPM

The TDS values for different water sources vary depending on whether the water is naturally occurring or comes from a treatment facility. There are many ways to measure TDS, the most common being the titration method.

Titration involves mixing known amounts of distilled water with a solution containing dissolved solids. The amount of solid that dissolves into the solution is then determined and compared to a standard reference table.

TDS readings indicate the total amount of dissolved solids in water, but they don’t tell us which types of solids are present. Some TDS are readily dissolvable in water and don’t pose health risks.

For example, carbon dioxide (CO), sulfate, chloride, potassium chloride, heavy metals, and radon can dissolve in water and are usually present in small amounts that are not harmful to human health. They tend to be rapidly removed from drinking water by filtration or activated carbon treatment.

These substances do not pose any threat to health because their concentration in drinking water is too low to cause any adverse health effects. In addition, some of these substances naturally occur and are present in ground and surface water as organic components of the water.

The EPA has set the Maximum Contaminant Levels (MCLs) for some contaminants in drinking water. For example, the MCL for lead is 15 µg/L. The MCLs generally refer to residential use, although the same MCLs may be applied for non-residential use.

In addition to MCLs, the EPA also sets MCLGs (Maximum Contaminant Level Goals) for drinking water. According to the EPA, “The highest MCLG is the level of a contaminant in drinkable water that does not pose a substantial health risk.”

Therefore, the EPA sets an MCLG based on the lowest level at which no adverse health effects are observed in people who drink large amounts of contaminated water over a long period.

For example, if it’s determined that one mg/L of lead causes no adverse health effects in people who drink large amounts over a long period, then the MCLG for lead is set at one mg/L.

How To Test for Total Dissolved Solids (TDS)

The most common method for measuring TDS is using a conductivity meter, which uses an electrical current to measure the ability of the water to conduct electricity. The higher the concentration of dissolved solids, the greater the electrical conductivity.

You can also measure TDS with a refractometer, which uses the principles of refraction to determine the dissolved solid content. While both methods are accurate, conductivity meters are more commonly used due to their ease of use and lower cost.

Health Effects of Drinking High TDS Water

Drinking water with a high concentration of dissolved solids, or TDS, can have adverse health effects.

For instance, ingesting high TDS water can lead to dehydration and gastrointestinal distress, as the body expends extra energy to process the solids.

In addition, high TDS water can damage tooth enamel and contribute to kidney stones. Furthermore, water with a high TDS level may contain harmful contaminants, including heavy metals and pesticides.

Ensuring you are drinking clean, safe water can help prevent health problems and save money in the long run, so it’s essential to be aware of the TDS level of your drinking water and take steps to filter out impurities.

Can You Get Zero TDS Water?

Zero TDS water is simply water with all of its dissolved solids removed. This can be achieved through reverse osmosis, which uses a semi-permeable membrane to filter out impurities.

While zero TDS water is safe to drink, it can be less healthy than water with a moderate level of dissolved solids. Zero TDS water can be unhealthy because many of the minerals and nutrients that are removed with the dissolved solids are beneficial.

How Do I Lower the Total Dissolved Solids in My Tap Water?

The easiest way to remove TDS from your tap water is to boil it before you drink it or use it for other tasks like cooking. You should only boil it for around 5 minutes as prolonged boiling can concentrate some of the remaining dissolved solids in the water.

However, boiling is a time-consuming and inefficient way of removing TDS from your tap water in the long term. Installing a water filtration system is a far better solution, and there are many different types to choose from.

Inline Filters

Inline Filters

These are installed in line with your faucet and use a filter cartridge that is regularly replaced. Inline filters reduce many different contaminants, including TDS, but they typically only filter out up to around 50-60 gallons of water.

Under-the-Sink Filters

Under-the-Sink Filters

These filters are installed under your sink and typically have higher filtration capacities than inline filters. They can filter up to 300 gallons of water before needing to be replaced. These filters are usually more expensive than the inline type, but they can last for much longer.

Sand Filters

Sand Filters

Sand filters can reduce the TDS in your water supply by removing sediment, which is often the most significant contributor to high levels of TDS. However, sand filters can be difficult to clean and maintain.

Most commercially available models require manually changing the sand every three months, so this may not be the most practical solution.

UF Filters

UF Filters

UF filters can remove most of the TDS from your water supply. They are widely used in homes today, however, UF filters aren’t as effective at removing certain contaminants like pharmaceuticals and hormones.

Reverse Osmosis Filters

Why Is My Reverse Osmosis Water Flow Slow

Reverse Osmosis (RO) filters are highly effective at reducing the levels of TDS and other impurities in water. They’re a great choice if your water is highly contaminated and if you live in an area with water that contains large volumes of naturally occurring minerals. However, RO systems are relatively expensive and require a lot of maintenance.

Still, installing an RO filter is the most reliable way to ensure your tap water contains safe levels of TDS. So, we’d say it’s worth investing in one if you have the budget for it.

Do Water Softeners Reduce TDS?

Water softeners do not reduce TDS because TDS is not a measure of hardness. TDS measures the number of dissolved solids in water, and hardness is just one type of dissolved solids.

Water softeners are designed to reduce the hardness of water rather than the levels of TDS present in the water. They focus on reducing certain minerals that cause hardness, such as calcium and magesium, and leave other TDS relatively untouched.

In fact, water softeners can increase the number of dissolved solids in your water by replacing calcium and magnesium with sodium.

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Scott Winfield
Scott Winfield
My name is Scott Winfield and researching and writing about water filters and other strategies to purify water has become my full time passion in recent years. I'm glad that you found our site and you can look forward to authoritative and well researched content here to help you get the best in water.
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