What Is TDS In Drinking Water, And Why Does It Matter?

Understanding TDS in Drinking Water

Total Dissolved Solids (TDS) refers to the concentration of dissolved substances in water, including both inorganic salts and small amounts of organic matter. These substances typically include minerals, like calcium, magnesium, sodium, and potassium, as well as anions, such as carbonate, chloride, sulphate, and nitrate. The TDS level is measured in parts per million (ppm) or milligrams per litre (mg/L).

TDS level serves as an indicator of water quality, reflecting the collective presence of various chemical contaminants, minerals, and salts resulting from natural sources, industrial discharge, agricultural runoff, or urban pollution. While drinking water, TDS itself is not a direct health risk; its concentration can affect the taste, odour, and appearance of water and may signal the presence of unwanted contaminants.

What Is TDS in Water?

TDS stands for total dissolved solids, which is a measure of all inorganic and organic substances dissolved in water at a molecular, ionised, or microgranular level. The major contributors to TDS include naturally occurring minerals from soil and rocks, urban and agricultural runoff, sewage, and industrial wastewater. Common TDS constituents are calcium, magnesium, sodium, and potassium (cations), and carbonate, chloride, sulphate, and nitrate (anions).

TDS levels provide a general picture of water purity but do not identify specific contaminants. For example, a high drinking water TDS reading may indicate excess minerals, salts, or even potentially harmful compounds. But further testing is needed to pinpoint the exact substances. TDS level is typically measured using a digital meter, which detects the concentration of dissolved ions.

Why Does TDS Matter for Drinking Water?

The TDS level in drinking water is a key indicator of its overall quality and palatability. Here's why drinking water TDS level matters:

• Taste and aesthetics: TDS directly influences the taste, smell, and appearance of water. Very low drinking water TDS levels may make water taste flat or bland, while high TDS can cause salty, bitter, or metallic flavours. It can also impact the water’s clarity and odour.
• Health implications: While minerals like calcium, magnesium, and potassium are beneficial, high TDS levels may signal the presence of harmful contaminants such as lead, arsenic, or nitrates. According to WHO, levels below 300 ppm are excellent, while those above 500 ppm may be unsafe.
• Appliance and plumbing impact: High TDS level causes scale buildup in water heaters, pipes, kettles, and washing machines. This buildup reduces efficiency, increases energy usage, leads to frequent breakdowns, and shortens an appliance's lifespan, raising both repair and replacement costs.
• Hydration and absorption: Imbalanced drinking water TDS can interfere with the body’s ability to absorb water and electrolytes properly. It affects hydration and potentially leads to digestive discomfort or mineral imbalances over time.
• Contamination detection: Sudden changes in TDS levels can be an early sign of contamination from sources like industrial discharge, sewage leaks, or agricultural runoff. Regular testing can help detect these issues before they pose health risks.

What Is the Best TDS Level for Drinking Water?

The ideal drinking water TDS level falls between 50 and 300 mg/L, offering the best balance of taste and acceptability. The EPA recommends a maximum TDS of 500 mg/L, beyond which water may become unpalatable. Levels above 1,000 mg/L are generally considered unsafe and may require advanced filtration. Extremely low TDS (<30 mg/L) can also produce flat-tasting water, though it poses no known health risks.

Health Effects of High or Low TDS

Extremely high TDS levels (above 1000 mg/L) can lead to excessive scaling in pipes, water heaters, boilers, and household appliances. It may also indicate the presence of toxic ions that can cause adverse health effects, such as waterborne diseases:

• Heavy metal ions, like lead, copper, manganese, and aluminium, can accumulate in the body and cause neurological disorders, organ damage, and developmental issues.
• Nitrate and nitrite ions in high TDS water can cause methemoglobinemia in infants.
• High sodium content may be problematic for those with heart or kidney conditions.
• Alters the taste of water, making it salty, bitter, or metallic.
• May discourage adequate water intake, increasing the risk of dehydration.

On the other end of the spectrum, water with extremely low TDS may not be ideal either:

• Missing minerals like calcium, magnesium, and potassium that support key body functions.
• Long-term use may lead to mineral deficiencies or electrolyte imbalance.
• It can reduce hydration efficiency, as demineralised water may not be absorbed effectively.
• Tends to taste flat or bland, which may discourage regular consumption.

However, it's important to note that the drinking water TDS level is not a direct indicator of water safety unless the specific ions are identified. Moderately low or high TDS alone doesn't mean the water is unsafe.

How to Measure TDS Level?

There are several ways to determine the TDS level in your drinking water:

1. Digital TDS Meter: This is the most reliable and popular method for home use. It’s a small handheld device with a probe that you dip into a water sample. Within seconds, it shows the TDS level in parts per million (ppm). Digital meters are affordable, simple to use, and provide accurate readings. They don’t require special skills or training, making them perfect for regular water testing.
2. TDS Test Strips: These are convenient and inexpensive paper strips that change colour when dipped into water. The colour corresponds to the approximate TDS level, which you can compare to a colour chart. Although test strips are less precise than digital meters, they offer a quick way to get a rough estimate of water quality.

To measure, fill a clean glass or container with water, then either dip the TDS meter’s probe or the test strip into the water. For meters, avoid touching the sides. Read the digital display or compare the strip’s colour to the chart.

How to Reduce High TDS in Water?

If your drinking water TDS level is higher than desired, here are some ways to reduce it:

• Reverse Osmosis (RO) Systems: One of the most effective methods, RO forces water through a semi-permeable membrane that removes up to 95-99% of dissolved solids, including salts, minerals, and contaminants. RO units are widely available for home use, but they may waste some water during filtration.
• Distillation: This process involves boiling water and condensing the steam back into liquid, leaving most dissolved solids behind. Distillers are effective but can be slow and use more energy, making them less convenient for everyday use.
• Deionisation (DI) Filters: These filters use ion-exchange resins to remove charged minerals and impurities, significantly lowering TDS. However, they’re typically used with other filtration methods and are less common in home settings.
• Water Softeners: Primarily designed to reduce hardness (calcium and magnesium), softeners exchange these minerals with sodium or potassium ions, which can reduce TDS related to hardness. However, it doesn’t remove all dissolved solids.
• Blending or Dilution: Mixing high-TDS water with low-TDS water can help reduce overall TDS to acceptable levels.

Choosing the right method depends on the water quality, budget, and usage needs. Regular testing is essential to ensure the drinking water TDS level stays within safe limits.

TDS in Packaged and RO Water: What You Should Know

Bottled mineral water often has TDS levels between 50 and 350 mg/L, with the minerals contributing to its taste and health benefits. However, some bottled water brands use purified water with added minerals, so check the label for the actual TDS level.

RO water typically has a very low TDS level, often below 50 mg/L. While this ensures high purity, the water may taste bland. Some RO systems have a remineralisation stage that adds beneficial minerals back into the water to improve taste and health benefits.

Conclusion: Why Monitoring TDS Is Essential for Healthy Living

Regularly monitoring the TDS level in your drinking water is a simple yet essential aspect of maintaining your family's health and well-being. While TDS is not a sole indicator of water safety, it provides valuable insights into overall water quality, taste, and the presence of contaminants. By understanding what TDS is in water and aiming for the ideal drinking water TDS range, you can make informed decisions about water filtration and ensure your loved ones consume clean, healthy, and palatable water.

If you're concerned about the TDS level in your drinking water or want to learn more about waterborne diseases and how to conduct water TDS tests, consider getting comprehensive water testing services.

With a network of advanced labs across India and a team of skilled technicians for at-home sample collection, Metropolis Healthcare provides accurate and comprehensive health check-ups to empower you in prioritising your well-being.

FAQs

1. What TDS is best for drinking water?

The best TDS level for drinking water is generally between 100 and 500 mg/L, balancing taste and mineral content. This drinking water TDS range ensures water is both palatable and nutritionally beneficial.

2. How much TDS in water is safe?

TDS below 1000 mg/L is considered safe. The EPA recommends a drinking water TDS limit of 500 mg/L for optimal taste and acceptability. However, specific contaminants at any TDS level can pose health risks.

3. Is 25 TDS safe for RO water?

Water with 25 mg/L TDS from RO is safe but may taste flat and lack beneficial minerals. Adding essential minerals is sometimes recommended to improve taste and nutritional value.

4. What if TDS is below 50?

TDS below 50 mg/L is not harmful but may result in an insipid taste and a lack of mineral content. It is still considered microbiologically safe. However, very low TDS can make water more corrosive to plumbing.

5. Is high TDS water harmful to health?

Extremely high TDS levels (above 1000 mg/L) may indicate the presence of harmful contaminants and lead to certain health concerns. However, moderately high TDS alone doesn't mean the water is unsafe, unless toxic ions are present.

6. Is low TDS water safe to drink?

Yes, low TDS level water is safe to drink and indicates high purity. However, prolonged consumption of water with extremely low TDS may potentially lead to mineral deficiencies.

7. What is the difference between TDS and hardness in water?

TDS measures all dissolved solids in water, including minerals, salts, and metals. Hardness specifically measures the dissolved calcium and magnesium content, which is a subset of the overall TDS level.

8. Does boiling water reduce TDS?

No, boiling water does not reduce TDS. It may even increase concentration as water evaporates, leaving dissolved solids behind. To lower the TDS level, methods like reverse osmosis, distillation, or deionisation are necessary.