What is Meant by Total Dissolved Solids?

Clean drinking water is one of the most vital resources for health and well-being. Yet, beyond visual clarity or taste, there’s a critical factor determining water quality—Total Dissolved Solids, often abbreviated as TDS. But what is meant by total dissolved solids? Why does TDS in water matter, and how does it impact health, industry, and purification systems?

This blog explores the meaning of TDS, how it’s measured, and why understanding TDS levels is essential for choosing the right water purification method—especially in the Indian context where water quality can vary drastically from one source to another.

What is Meant by Total Dissolved Solids?

Total Dissolved Solids (TDS) refers to the combined content of all inorganic and organic substances dissolved in water. These substances exist in a molecular, ionized, or micro-granular (colloidal sol) suspended form. Typically, TDS includes minerals, salts, metals, cations (positively charged ions), and anions (negatively charged ions).

The major contributors to TDS in water include:

• Calcium

• Magnesium

• Potassium

• Chlorides

• Bicarbonates

• Sulfates

• Nitrates

• Silica

• Heavy metals (in contaminated areas)

Water naturally acquires these dissolved solids as it travels through soil, rocks, and pipelines. Human activities like agriculture (fertilizer runoff), industrial discharge, sewage, and even road salt in urban areas can also contribute significantly.

TDS is not a pollutant by itself, but high or low TDS levels can indicate possible contamination or poor water quality.

Why is TDS Important in Water?

Understanding TDS in water is crucial for multiple reasons:

1. Taste and Aesthetics

TDS levels directly affect the taste, odor, and appearance of water. Water with low TDS may taste flat, while high TDS can cause salty, metallic, or bitter tastes.

• Low TDS (<50 ppm): Often tasteless or slightly sour

• High TDS (>500 ppm): Can taste bitter or metallic, especially due to excess calcium, iron, or sulfates

2. Health Effects

TDS by itself isn’t always harmful, but extreme levels can be problematic:

• Very low TDS: May lack essential minerals like calcium and magnesium, affecting metabolic functions.

• Very high TDS: Could contain harmful heavy metals, salts, or chemicals like arsenic, nitrates, and lead.

Therefore, monitoring and maintaining an optimal TDS level ensures not just taste, but safe, mineral-balanced water.

3. Appliance Efficiency and Scaling

High TDS leads to scale buildup in pipes, geysers, and appliances like washing machines, increasing maintenance costs and lowering efficiency.

4. Industry Standards

Industries like pharmaceuticals, electronics, and food processing require ultra-pure water. In such cases, knowing the TDS level is not just important—it’s mandatory for compliance.

Ideal TDS Level for Drinking Water

So, what is the ideal TDS level for drinking water?

According to the Bureau of Indian Standards (BIS) and World Health Organization (WHO), the classification of TDS in water is as follows:

The ideal TDS range is considered 150 to 300 ppm, which provides both good taste and sufficient mineral content.

Note: RO systems often reduce TDS to <50 ppm, which may strip beneficial minerals. In such cases, a TDS controller or mineral cartridge is recommended.

How to Measure TDS in Water

Accurate measurement of TDS is key to knowing your water quality and choosing the right purification method.

1. TDS Meter (Digital)

A portable, battery-operated device that measures the electrical conductivity of water. TDS is calculated in parts per million (ppm) or mg/L.

• Pros: Affordable, quick readings, easy to use

• Cons: Cannot identify which substances are present—only total count

2. Laboratory Testing

Professional water testing kits or labs can provide a complete water profile, identifying specific ions, heavy metals, and contaminants.

• Pros: Accurate and comprehensive

• Cons: More expensive and time-consuming

3. In-line TDS Monitors

Used in industrial RO systems and commercial buildings, these provide real-time TDS readings before and after purification.

TDS in Different Water Sources

The TDS level can vary significantly depending on the source of water:

1. Tap Water

Generally treated and disinfected, but can still have moderate TDS depending on pipeline infrastructure and source.

2. Borewell Water

Often high in minerals, salts, and sometimes heavy metals. May require strong RO purification.

3. Surface Water (Rivers/Lakes)

May have moderate TDS, but prone to microbial and chemical pollution.

How to Control or Reduce TDS

If your water has a high TDS level (above 500 ppm), you’ll need to consider water treatment options:

1. Reverse Osmosis (RO)

The most effective method for reducing TDS. RO membranes filter out up to 95–99% of dissolved solids, including salts, metals, and chemicals.

• Best for borewell or high-TDS tap water

• Needs regular maintenance

2. Activated Carbon Filters

These remove organic matter and chlorine, but have limited effect on TDS.

• Best as a pre-filter in combination systems

3. Deionization (DI)

Used in labs and industries to remove all ions. Not practical for domestic use.

4. TDS Controller or Mineral Cartridge

Used alongside RO to retain essential minerals while lowering TDS. This ensures that water doesn’t taste flat or become mineral-deficient.

Also Read - What is the Minimum TDS for Drinking Water? A Complete Guide

RO Systems and TDS: A Balanced Approach

When choosing a water purifier, don’t just aim for “zero TDS.” Instead, aim for a balanced TDS level suitable for drinking and health.

Most modern RO systems come with:

• TDS Controllers: Adjust the TDS level of output water.

• Remineralization Filters: Add back calcium and magnesium.

• Digital TDS Meters: Help monitor water quality in real time.

Always test your input water’s TDS before selecting a purifier model. If your TDS is already below 300 ppm, UV+UF or UF-only systems may suffice—RO might be overkill and waste more water.

FAQs: What People Also Ask

Q1. What are Total Dissolved Solids in water?

Total Dissolved Solids (TDS) refer to all inorganic and organic substances dissolved in water, including salts, minerals, and metals.

Q2. What is the ideal TDS level for drinking water?

The ideal TDS level is between 150–300 ppm. Water below 50 ppm may lack minerals, while above 500 ppm could be harmful.

Q3. Is high TDS water safe to drink?

Not always. High TDS water may contain harmful substances like arsenic or lead. It’s best to purify water with a high TDS value using RO systems.

Q4. How do I reduce TDS in my home water?

Install a reverse osmosis (RO) water purifier, preferably with a TDS controller or remineralizer to maintain essential minerals.

Q5. Can I drink low TDS water daily?

Yes, but it should still contain essential minerals. Ultra-low TDS water (<50 ppm) may lack beneficial nutrients, so choose a purifier that adds minerals back.

Also Read - Is 25 TDS Safe for Drinking Water?

Conclusion

Understanding what is meant by total dissolved solids is essential for anyone who values water quality—whether you’re choosing a purifier for home use or managing a commercial water treatment system.

TDS levels offer a snapshot of water purity, affecting taste, safety, and even appliance longevity. With tools to measure and control TDS, you can make informed decisions and ensure that your water isn’t just clear—it’s clean, balanced, and beneficial.

Always test your source water, consult BIS guidelines, and use purification technologies that retain vital minerals while removing harmful substances. In today’s world, knowing your water’s TDS is no longer optional—it’s necessary.