What is TDS in Water?

TDS, or Total Dissolved Solids, measures the amount of solid particles suspended in water. It is usually expressed in parts per million (ppm) and is essential when assessing drinking water quality. TDS levels can also be used to assess the mineral content of water, including calcium, magnesium, sodium, chloride, and other inorganic compounds. High TDS levels can indicate the presence of contaminants such as heavy metals and organic matter, making water unsafe to drink. Poor-quality water with high levels of TDS can cause gastrointestinal illnesses or other symptoms of waterborne disease.

What Is TDS In Water?

Total Dissolved Solids (TDS) are the total amount of mobile charged ions, including minerals, salts, or metals dissolved in a given volume of water. These ions can come from various sources, such as agricultural runoff, industrial waste, sewage, and natural deposits. High TDS levels can create an unpleasant taste and smell in drinking water and cause staining or scale buildup in plumbing fixtures.

How Do These Solids End Up Dissolved In Water?

TDS in water is mainly composed of dissolved solids that come from a variety of sources. These can be natural, such as decaying vegetation, rocks, and soils, or they can originate from human activities like industrial waste discharge, agricultural runoff, sewage effluent, and atmospheric deposition. The amount of TDS present in the water will vary depending on the geographical area, water source, and how it was treated before distribution.

What Happens To The Water When The TDS Level Is High?

When the TDS level is high, it can lead to many unwanted side effects. High levels of total dissolved solids in water can cause various problems, such as discoloration, unpleasant odors, and even scale buildup on pipes and fixtures. In addition, high TDS levels may make the water taste salty or metallic. Furthermore, it can lead to decreased water pressure and make it difficult for soap to lather or rinse away properly. High levels of TDS in water may also cause health problems as some impurities become more concentrated, increasing the risk of exposure to harmful chemicals like arsenic and heavy metals.

How Can Water Treatment Facilities Remove TDS?

Water treatment facilities use physical, chemical, and biological methods to reduce total dissolved solids (TDS) in water.

  • Physical methods include filtration and sedimentation. Filtration involves passing water through filters designed to remove large particles such as dirt, sand, and silt. Sedimentation is the process of allowing suspended particles to settle out, which is usually done in a settling tank.
  • Chemical methods include pH adjustment, coagulation and flocculation, and chemical precipitation. In the pH adjustment method, chemicals are added to water to adjust its acidity or alkalinity level. This changes the solubility of some TDS so they can be removed from the water.
  • Biological methods such as activated sludge treatment involve using microorganisms to break down organic compounds. The by-products of this process are then removed from the water using physical and chemical methods.

TDS Level For Drinking Water

TDS Level in parts per million(ppm) Palatability Quotient

Between 50-150 Excellent for drinking
150-250 Good
250-300 Fair
300-500 Poor
Above 1200 Unacceptable


Sources Of Total Dissolved Solids

  • The natural source of TDS in drinking water is usually the mineral content of rocks and soil it comes into contact with. As water passes through underground aquifers, it takes on minerals from these sources and carries them into surface water supplies. Other natural sources of TDS include organic matter, such as decaying vegetation and aquatic life forms.
  • Artificial sources of TDS in drinking water include industrial effluent and agricultural runoff. The industrial waste can leach into groundwater and be discharged directly into surface water supplies. Agricultural runoff contains fertilizers, pesticides, animal wastes, and other contaminants. Chlorination is often used to treat drinking water to reduce TDS levels, although this can lead to other problems if not done correctly.

How Is TDS Measured?

TDS levels are measured in parts per million (ppm), usually ranging from 30 to 500 ppm. The higher the concentration, the more contaminants are present in the water. TDS meters or total dissolved solids testers can measure the TDS level in a sample. These devices measure electrical conductivity and display an estimation of the TDS content.

Why Should You Measure Total Dissolved Solids?

  • Taste and smell: Total dissolved solids are responsible for the taste and smell of water. When the levels of TDS in water increase, it can give the water a bitter or salty taste.
  • Health: Total dissolved solids (TDS) in drinking water is an important factor to consider when looking at the quality of the water. A lower TDS content is generally better for human health, as fewer minerals and chemicals are present in the water. High levels of TDS can be dangerous, as they may contain heavy metals or other contaminants.
  • Filter maintenance: It is essential to regularly maintain your water filter system to ensure water safety and quality. This includes replacing the filter cartridges, changing out sediment pre-filters, and cleaning other filter components.
  • Plumbing and appliances: Total Dissolved Solids (TDS) measure the amount of minerals, salts, and other substances dissolved in water. High levels of TDS in drinking water can lead to mineral deposits on plumbing fixtures, affecting their performance and increasing the time and effort needed for regular cleaning. The presence of high TDS can also make appliances such as washing machines and dishwashers less efficient, leading to a decrease in their performance.
  • Cooking: Total Dissolved Solids (TDS) in water is important to consider when cooking. The level of TDS can affect the taste, texture, and overall quality of food. Similarly, low-TDS water can cause mineral deposits in certain cooking dishes, such as tea kettles.
  • Pools and Spas: Total Dissolved Solids (TDS) are an essential measure of water quality in swimming pools and hot tubs. It measures the combined content of all inorganic and organic substances in the water, including minerals, salts, or metals such as calcium, magnesium, sodium, and potassium.
  • Hardness: Total Dissolved Solids (TDS) indicate the amount of minerals dissolved in water. The higher the TDS level, the more complex the water. Elevated levels of TDS can cause a bitter taste and issues with plumbing fixtures due to scale buildup. High levels may also indicate other pollutants that can harm your health.
  • Car Washing and Window Cleaning: TDS (Total Dissolved Solids) are minerals, salts, and other substances found in water. TDS levels in tap water can be as high as 1000 ppm or more. For car washing, window cleaning, and similar activities, it is important to use water with a low TDS level – below 500 ppm so that spots and streaks do not appear on the surfaces being washed.

How To Reduce TDS In Water

  • RO: Reverse osmosis is a process where water passes through a semi-permeable membrane, which blocks minerals and other ions from passing through. The now pure water can then be collected for use.
  • Water distillation: This process is used in areas with high levels of Total Dissolved Solids (TDS) to reduce water’s solids. This method involves heating and cooling the water, which causes suspended particles to settle and be removed. The remaining water is sent through a filter that removes any additional sediments or contaminants.
  • Deionization: Deionization is a process used to remove ions (charged atoms or molecules) from the water, thus reducing its levels of dissolved solids. It relies on ion exchange resins which attract and trap particles from the water before releasing them into an acidic or alkaline solution, depending on the resin type.


Is low TDS water harmful?

No, low TDS water is not harmful. It can provide numerous health benefits, such as reducing kidney stones risk and helping regulate blood pressure levels. Low TDS water can also improve the taste of food and beverages due to its lack of chemical contaminants.

Is water with high mineral content healthier?

Some people believe that water with a high concentration of minerals, such as Total Dissolved Solids (TDS), is healthier and provides more benefits than regular drinking water. TDS measures the combined content of all inorganic and organic substances in a liquid in molecular, ionized, or micro-granular suspended form.

What should be the TDS of water for concrete?

The TDS of water used for concrete and other cement-based materials should be below 500 mg/L to ensure the highest quality of the finished product. Although this is not an absolute requirement, it is recommended since high levels of TDS can lead to poor workability, increased shrinkage and cracking, and lower strength in concrete.

My drinking water is contaminated. What do I do?

If your drinking water is contaminated, you should take to test it for Total Dissolved Solids (TDS). TDS in water measures all the solids dissolved in a given volume of water. This includes organic and inorganic compounds such as calcium, magnesium, potassium, chloride, nitrate, sulfate, bicarbonates, and phosphates.

Should I purchase a TDS meter to test my tap water?

It is a personal choice whether or not to purchase a TDS meter to test your tap water’s quality. There are some factors to consider, such as cost and availability. TDS meters measure the total dissolved solids (TDS) in water, indicating your water’s overall mineral content and purity.

Is water with high mineral content healthier?

Some minerals can be beneficial for health, but higher concentrations of certain minerals, such as those found in water with high Total Dissolved Solids (TDS), can cause adverse health effects. Water with high TDS contains higher contaminants that may not be safe to drink or use for everyday purposes.


Assessing RO Water Quality - infographic
Assessing RO Water Quality – infographic

Total Dissolved Solids (TDS) are an important chemical measurement in water. TDS affects the taste of the water and can provide a measure of its purity. High TDS levels can lead to hardness, scale deposits in pipes, and other problems such as corrosion. Low TDS levels may indicate that water has been over-treated, which can affect its taste. It is important to monitor and control the amount of TDS in drinking water for health and safety reasons.

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