What is the best TDS level for Ro-filtered Water?

The confusion over what TDS means is understandable. It stands for total dissolved solids, which are made of dissolved particles and solid materials in water.

Water is a universal solvent because it can dissolve things and can have particles in it, called total dissolved solids (TDS).

Dissolved solids are either organic or inorganic. Understanding what fluids you have and their TDS levels tells you about the water quality.

The TDS levels in your water may vary depending on the source. Well water tends to have higher levels of TDS over both tank or municipal water sources.

TDS levels can range anywhere between 50-2000ppm. Not all levels of TDS in water are harmful for human consumption. Hence, it becomes critical to understand the significance of various levels of TDS.

What is TDS in water?

Total dissolved solids (TDS) is the term used to describe the inorganic salts and small amounts of organic matter present in solution in water.

TDS in water can come from just about anywhere, including natural water springs, chemicals used to treat the municipal water supply, runoff from roads and yards, and even your home plumbing system.

Types of total dissolved solids

The following list details common total dissolved solids that may be present in your water.

  • Calcium
  • Chloride
  • Magnesium
  • Potassium
  • Zinc
  • Aluminum
  • Copper
  • Lead
  • Arsenic
  • Iron
  • Chlorine
  • Sodium
  • Fluoride
  • Bicarbonates
  • Sulfates
  • Pesticides
  • Herbicides

Sources of total dissolved solids

Total dissolved solids come from many sources, both natural and artificial. Natural sources of TDS include springs, lakes, rivers, plants, and soil. For example, when water flows underground in a natural spring, it absorbs minerals, such as calcium, magnesium, and potassium, from rocks.

On the other hand, the effects of human activity can also produce total dissolved solids in water. Pesticides and herbicides may come from agricultural runoff, lead may come from old plumbing pipes, and chlorine may come from water treatment plants.

Total dissolved solids are even purposefully added to water sometimes, as bottled mineral water you come across in the grocery store may contain mineral additives.

Consumable Level

The World Health Organization states that an acceptable range for the TDS level of water should be up to 300 parts per million (ppm) to be suitable for human consumption.

Water with a TDS level higher than 300 ppm may not be palatable. It can taste salty and may contain a high concentration of minerals like sodium, potassium, and other salts.

Any measurement reaching beyond 300ppm would ideally require an additional Reverse Osmosis Technology for the purification of water.

RO water purifiers use special membranes that hold back many dissolved solids to give only palatable, purified water.

Unsafe Level

Water indicating a TDS level beyond 1000ppm may be unsafe for human consumption. As per WHO, TDS levels beyond 1200ppm are considered unacceptable.

Water with a high level of TDS impacts the color, odor, and taste dramatical. It may be highly unpalatable.

In addition to the taste, water with a high TDS level may not be suitable due to the excessive scaling caused by it in water pipes, heaters, boilers, and household appliances.

In a study by the World Health Organization, a panel of tasters came to the following conclusions about the preferable level of TDS in water

Level of TDS (milligrams per litre) Rating
Less than 300 Excellent
300-600 Good
600-900 Fair
900-1,200 Poor
Above 1,200 Unacceptable


How is TDS measured?

How is TDS measured?Now that you know what TDS is, its impact and how it may affect you, you are worried and want to measure the level of TDS in your water.

But how? Usually, TDS are measured in a laboratory where a sample will be filtered, dried, and heated to determine how much TDS is present.

But if you have a reverse osmosis system, you can use the following formula to calculate the percent rejection of TDS and measure your RO system’s performance.

Measure the TDS of raw feed water by submersing the tester’s probes into a glass of tap water. Record the results.

Measure the TDS of your RO water by filling a glass with RO water (from the RO faucet) and submersing the tester’s probes into the water. Record the results.

Calculate percent rejection using the following formula:

%Rejection = ((Tap TDS – RO TDS)/(Tap TDS)) *100

NB: If your RO system is new or the membrane has been replaced, do not test the first tank of RO water. The first tank will contain sanitizer and possibly carbon fines from your new filters that will cause a false reading.

Why should you measure total dissolved solids?

Total dissolved solids can affect your water quality, health, home plumbing system, and even daily tasks, such as cooking and cleaning.

By measuring your water for TDS, you can better understand your water quality and how it affects your everyday life.

This allows you to make an informed decision to solve your water quality problem and install the most effective filtration system for your home.

Taste and smell

Tap water with a high concentration of total dissolved solids (TDS) can have a bitter taste and unpleasant smell. The higher the concentration of total dissolved solids, the more painful your water will be.


A  reverse osmosis system and a ceramic water filter are recommended to improve the taste and smell of bitter tap water.


High TDS water is not necessarily unhealthy to drink, but certain substances, such as lead and copper, are health hazards.

For example, lead exposure can cause brain and nervous system damage, and high levels of copper exposure can cause nausea.


A reverse osmosis system or a water distiller is recommended to filter heavy metals.

Filter maintenance

Water filtration systems are a great solution to reduce total dissolved solids but are subject to normal wear and tear.

Routine testing for TDS can assure that your filter system is working correctly and alerts you when required.

 Plumbing and appliances

Water containing high levels of dissolved calcium and magnesium is hard water and can result in high TDS levels. When calcium and magnesium salts dissolve, they collect in pipes and form scale buildup, which results in costly pipe replacements and shortens the lives of your appliances.


A water softener is recommended to filter calcium and magnesium and can prevent scale buildup.


Though not detrimental to your health at levels below 1000 ppm, cooking with high TDS water can change food taste. For example, if your water has high chlorine levels, you may find that your pasta absorbs an unpleasant taste from the boiling water.


A carbon filter is a practical choice to remove chlorine from water.

How to reduce TDS in water

Specific water treatment systems are effective methods to reduce or remove TDS from water, especially if the TDS level is 500 ppm or higher.

Many helpful filtration systems depend on the type of TDS your water contains, but reverse osmosis systems, water distillers, and deionization are comprehensive systems that can reduce the majority of total dissolved solids.


 Reverse osmosis

Reverse osmosisA reverse osmosis (RO) system is one of the most comprehensive filters to remove contaminants. It uses pressure to push unfiltered water through a semipermeable membrane.

The membrane has tiny pores that block contaminants, such as total dissolved solids, but allow clean water to flow through to the other side.

Where to buy

If you’re interested in getting a  reverse osmosis (RO) system , you can buy from Amazon through the link below.



Water distillation

Water distillationDistillation is a water treatment method that mimics how water is purified in nature: through evaporation in the atmosphere.

Water distillers convert water into steam, eliminating total dissolved solids and other contaminants because they cannot turn into steam as water can. Once the water returns to its liquid form, it is contaminant-free.

Where to buy

If you’re interested in getting a Water distiller, you can buy from Amazon through the link below.




DeionizationDeionization systems remove total dissolved solids through ion exchange, using resins that control ions’ electrical charge.

Water ions replace charged ions from total dissolved solids. The water produced is highly pure, so deionization cartridges are often referred to as high purity filters.

Where to buy

If you’re interested in getting a Deionization systems, you can buy from Amazon through the link below.


Wrap Up

RO water purification is the most effective technology in reducing the TDS of water and further enhancing water taste.

There is a misconception that RO water purifiers altogether remove the TDS. It is crucial to understand that RO water purifiers reduce TDS levels to bring them down to acceptable levels, making them palatable to drink.

Hence, if your source water’s TDS level is high (>300ppm), you must install a water purifier with RO technology.

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