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Don’t drink a drop until you know the TDS in your water

TDS is a measurement of the total dissolved solids in water. The higher the TDS, the more impurities are present.

The quality of your drinking water can have a significant impact on your health and well-being. Many people don’t realize how many different sources there are for impurities in their drinking water and whether their tap water meets the safe standards for consumption.

Even in the United States, there is no guarantee of perfect water quality, regardless of the source.

If you want clean pure water for drinking and cooking, it’s important that you know how much TDS is in your tap or bottled water before you use it.

What is the TDS in your water?

What is Total Dissolved Solids?

Aside from visible impurities like sand or debris, there are dissolved molecules of many different substances mixed with water. When all these dissolved solids are measured, they are referred to as “total dissolved solids” or TDS.

Total dissolved solids (TDS) are usually made up of inorganic salts, metals, and organic matter. It is also referred to as the sum of cations and ions present in water molecules.

While not all of the possible substances are considered dangerous, the presence of these materials indicates a higher level of contamination than if there were no total dissolved solids present.

Inorganic Salts

There are common inorganic salts and metals present in water that form the total dissolved solids TDS concentrations.

These inorganic salts and metals often come from natural sources like dissolved rocks but harmful compounds based on these elements can come from pollution. Regardless, their presence of dissolved ions and other substances will influence the level of TDS.


Calcium is an important mineral for us to consume and a building block for bones and teeth.

Calcium comes from dissolved rocks like limestone, marble, fluorite and many more making it one of the primary components of TDS in water.

Calcium also contributes to making water more alkaline. Alkaline water in moderation can be considered healthy.


Magnesium can be found in many products including cattle feed and fertilizers.

It is necessary for plants to perform photosynthesis, but it doesn’t harm humans through drinking water even if increases the TDS level.


When minerals are dissolved through the weathering process, potassium is produced.

Potassium has many functions which include nerve and muscle function. This element also helps with human activities like digestion, making protein in the blood, and producing energy for cells to use.

However, skin contact with potassium metal can lead to caustic potash corrosion which is more harmful than acid corrosion.


Sodium is used in various industries including agriculture, metallurgy, textiles, food, and soap.

It is beneficial to animals, much like potassium. However, if you have heart or kidney disease, you need to avoid consuming too much.

Beneficial minerals are part of TDS


Bicarbonates are a chemical that is used to make the pH of public drinking water more neutral or basic. This helps maintain its quality; ensuring no harmful bacteria can grow as well as giving it a more enjoyable taste.


Common chlorides like NaCl and KCl come from natural salt deposits and are a common component in TDS.

Chlorides have salty or brackish taste and they are corrosive to water pipes.

Drinking water with a minimum level of chlorides is beneficial for the body but if the salt content reaches higher levels, it becomes harmful.


Sulfates can lead to scale buildup in pipes and taste bitter at high levels in drinking water.

When taken in high doses, it produces a laxative effect on humans and animals so it is not a desirable element in TDS.

Organic Matter

The water you drink can contain organic matter. This includes microscopic and decomposed plants, animals, bacteria, and fungi that may be invisible to the naked eye.

The amount of organic matter can vary tremendously from one body of water to another, depending on where it comes from and how much pollution it has absorbed along the way.

Dissolved organic matter is measured with total dissolved solids and it is clearly better to have a very low amount of these compounds in your water.

Where Total Dissolved Solids TDS in Water Come From?

What is the normal TDS in water?

Although the purest water is without impurities and has zero TDS, it is a fact that there dissolved solids in water. These particles can contaminate water in many ways before it reaches your tap.

Keep in mind that even municipal (city) water that has been through a water treatment process before arrive at your home can have a high TDS.

Natural Water Supplies

Most of the total dissolved solids level start with the water source.

Dissolved rocks mix with water and then accumulate in various bodies of surface water. It could be a lake, river or reservoir; all natural bodies of water have dissolved solids.

Mineral Springs

Spring water is stored underground. This means that the water comes into contact with various rocks and minerals thus leading to the dissolved solids mixing in the spring water as part of the TDS.

Many of the minerals in otherwise clean spring water are considered beneficial, which is why bottled mineral water is so popular.

Carbonate Deposits

Whenever water passes through carbonate deposits like limestone, the surface of these deposits will mix with water.

TDS test often shows traces of carbonate deposits in water.

Salt Deposits

Once water is exposed to salt deposits, it elevates the TDS in the water.

Sea Water Intrusion

Whether it is underground water or river water near the sea, there are instances when sea water combines or compromises freshwater mixing with dissolved solids from sea water along the way.


Most sewage wastewater discharges to a river or stream. This will increase the TDS in the water.

Urban Run-off

Rainwater in urban areas mixes with various surface solids, chemicals, and minerals. This increases TDS before they collect in larger bodies of water.

Agricultural Run-off

Chemicals used heavily in agriculture, such as phosphates, can travel to the water supply and affect the quality of what you get from the tap.

Storm Water

Storms and hurricanes not only carry huge amounts of water from the sea and other large bodies of water. They also carry debris and solid particles from these sources and mix these particles with the water supply, thus contributing to higher TDS levels.

Industrial Wastewater

Industrial wastewater is mixed with various chemicals used during manufacturing. They are often released in the sea or rivers introducing more dissolved solids.

Chemicals Used in Water Treatment Plants

Water treatment requires the use of chemicals like chlorine to treat contaminants and improve drinking water quality. Unfortunately, this leads to higher TDS in the water after treatment and possible new issues to the water supply.

Leaching from pipes

You might be surprised that the plumbing system is also responsible for increasing the water’s total dissolved solids.

Pipes can accumulate various minerals and release chemicals from corrosion that contribute to high level of TDS in water.

How to Measure TDS Water?

A total dissolved solids test can be done at home with a simple TDS meter (or TDS tester).

A TDS Meter uses the electrical conductivity of the water to measure total dissolved solids levels.

What is a TDS Meter?

What is a TDS meter?

Most of the TDS Meters in the market are a small hand-held device that takes measurement of TDS levels through testing conductivity of the ions and cations in a solution.

A TDS Meter will give numerical results in Parts Per Million (ppm) or mg/L of TDS. Any amount of dissolved solids higher than 500 ppm concentrations can be hazardous.

Unfortunately, the TDS reading only measures the ions and cations but does not identify specific contaminants or dangerous chemicals. You have to conduct separate water tests if you want to know more about the dangers in your water.

How to Use a TDS Meter?

To use a TDS meter, collect a water sample in a clean container and put the tip of the meter in the water. Start the test (usually with the push of a button) and wait to see the TDS reading.

You do not have to put the whole meter in the water but only the sensor on the tip.

What are the Effects of TDS in Water?

Dissolved solids produce different effects in the water since some particles are harmful while others are beneficial in the human body.

It all depends on the nature of total dissolved solids as well as the levels present in the water.

Keep in mind that TDS measurements are only a general assessment of the overall water quality and does not provide specific details about what is in the water and whether it is dangerous.

Total Dissolved Solids (TDS) chart

Does TDS Affects Water pH?

Water pH is the measure of hydrogen ions in the water, and TDS does not affect the pH in the same way.

However, if the TDS contains carbonate, bicarbonate, CO2, calcite or gypsum, the pH could increase or decrease.

This means that not all TDS can affect the pH but there are specific TDS which can greatly influence the pH depending on how it interacts with the hydrogen ions present in the water.

You need to know the specific substances included in the total dissolved solids to determine if it can affect the pH of your water or conduct a separate pH test.

What are the Effects of Low TDS Level?

Low TDS levels often means higher water quality.

The water has very few dissolved impurities mixed in with the water molecules which make it ideal for drinking and cooking.

Water with a low TDS level is very clear and will have less taste and smell.

However, it is generally fine to have beneficial minerals in the water and some people believe that a lack of dissolved minerals is not beneficial.

What are the Effects of High Water Total Dissolved Solids?

For plants, animals and humans, intake of water with high TDS level can be a health hazard.

The most noticeable change in water with high a TDS level is a bitter or salty taste, discoloration, or smell.

High total dissolved solids often leave precipitates on fixtures which can compromise the function of the fixture or the entire system.

It is common for corrosion to occur on fixtures when exposed to water with high TDS parts per million (ppm).

Another effect of high TDS water is reduced water filtration system efficiency due to clogging of solids in the filters. Some water sources require pre-filters just to lower the TDS level before another filtration system can remove more dangerous chemicals.

What are the Health Effects of TDS on Animals and Humans?

Some dissolved solids like calcium and magnesium can provide animals and humans the necessary elements to promote healthy body functions and structure.

Unfortunately, there are also chemical particles and substances which are toxic and fatal to animals and human health.

Most of the TDS substances in your tap water are safe for consumption if you have municipal/city water and those with wells should be more careful.

How Does TDS in Water Affects Plants?

Some dissolved solids in the water like those present in fertilizers are beneficial to plants.

However, some substances are toxic and can inhibit growth, productivity or even lead to death.

Many plants will benefit from getting only mineral or filtered low TDS water.

What TDS is Best for Drinking Water?

Theoretically, the best drinking water is the one with a low TDS level according to the World Health Organization (WHO) and Environmental Protection Agency (EPA).

The WHO states that a TDS level of less than 300 mg/L is “excellent” and from 300-600 is “good.” More than 600 is only “fair” or worse.

The EPA suggests that the TDS level should be under 500 mg/L.

However, if only dissolved solids that are considered beneficial are present, the ideal level is between 50-150 mg/L or ppm.

How to Reduce TDS Levels

There are a ways to reduce TDS in drinking water, but they are not always practical.

However, the first step is to test your water so you know exactly what you are dealing with.

Test your water for TDS

Test the Water TDS Level

It is a good idea to test the water before and after installing a filtration system.

You can order a simple TDS meter and test for TDS yourself. Any TDS level over about 500 ppm is considered questionable, so this is a good starting point.

If you have high TDS water, you probably have other non-TDS chemicals and pollutants in your water as well.

Conduct Comprehensive Water Test

To really understand your water, it is better to have your tap water professionally tested.

You can either request help from water experts to take samples or order a water testing kit, where you collect a sample and mail it into a lab. The latter is often less expensive.

Aside from measuring the total dissolved solids TDS level in water, you should to check for other pollutants present in the water before you decide on a solution.

This will give you a comprehensive view on the potential dangers and harmful substances present in the drinking water.

Determine which Contaminants to Remove or Allow

If you know the contaminants present in your water, you can carefully check if each of these is toxic or beneficial.

Some of the dangerous chemicals that may be present in tap water are measured by a TDS meter. Substances such as arsenic, fluoride, hexavalent chromium, PFAS, and radium would require more detailed testing.

You do not have to remove all of them and can leave healthy minerals in the drinking water while finding ways to remove the contaminants that are harmful according to drinking water regulations.

Identify Solutions

If you know which contaminants you want/need to remove, you can identify the appropriate solutions.

Some possible solutions include:

  • Change your water source. Some people have the option of city or well water.
  • Use bottled water. This is an easy fix, but the cost, effort, and waste to buy, move, and dispose of all those bottles adds up fast.
  • Install a point-of-use water filter. Filtration systems in just your kitchen will allow you to filter only the water you need for cooking and drinking.
  • Install a whole house water filter. These systems will remove the contaminant load, improve taste and smell, as well as improve water quality everywhere in your house.

Install a Filtration System

NU Aqua Water Filters
Undersink RO System

The best way to reduce TDS is to use a high quality water filter. It is the most effective method of removing contaminants in the water and lowering high TDS without going through the trouble of finding a new water source.

In particular, reverse osmosis filters (RO systems) are the best filters to remove most of the chemicals in the water and are easy to find and install in the United States.

Reverse osmosis (RO) is a type of water filter that blocks practically all contaminants during the filtration process. RO filters are often paired with a carbon filter in one package to produce the purest possible output.

The TDS range of RO water should be extremely low. Measurements of less than 20 mg/L is common for reverse osmosis water.

In face, the TDS of RO filtered water is so low, many people choose to remineralize reverse osmosis water to add back some of the beneficial trace minerals that actually raise TDS levels.

Whole house water filter systems are also very effective at lowering tap water total dissolved solids everywhere in your home.

Enjoy Safe and Clean Water

Once you successfully lower the total dissolved solids in your drinking water and achieve the ideal water quality and taste, you can be sure you are drinking safe, clean and healthy water at home.