In the modern era of health awareness and water safety, understanding what constitutes safe drinking water is crucial. One of the most frequently asked questions is: “What is the acceptable TDS level in drinking water?” TDS, or Total Dissolved Solids, refers to the amount of organic and inorganic matter dissolved in water. These substances can range from essential minerals like calcium and magnesium to harmful elements such as heavy metals or industrial salts.
Monitoring and managing TDS in water is essential for ensuring the health and safety of consumers, maintaining appliance longevity, and complying with national and global water quality standards. This comprehensive guide explores everything from the basics of TDS, health implications, measurement techniques, acceptable standards, and methods for controlling TDS in residential and commercial applications.
What is TDS in Water?
Total Dissolved Solids (TDS) represent all the dissolved substances in water, including:
- Essential minerals like calcium, magnesium, potassium, and sodium.
- Inorganic salts such as bicarbonates, chlorides, and sulfates.
- Organic matter including pollutants and agricultural residues.
- Heavy metals like lead, arsenic, and mercury in contaminated sources.
TDS is measured in milligrams per liter (mg/L) or parts per million (ppm), and the concentration can affect the taste, safety, and usability of the water.
Why TDS Levels Matter in Drinking Water
Water is not just a thirst-quencher — it’s a vital part of our body’s nutrient system. While certain minerals in water are essential for health, excessively high or extremely low TDS levels can lead to health issues and damage water systems and appliances.
⚠ Health Effects of High TDS in Water
High TDS levels often indicate excessive minerals or contaminants:
- Sodium: Increases the risk of hypertension and heart disease.
- Chlorides and Sulfates: May lead to gastrointestinal issues.
- Nitrates and Heavy Metals: Can be toxic, especially for children and pregnant women.
🛑 Health Risks of Low TDS Water
Extremely low TDS (<50 mg/L) means the water is almost entirely demineralized, which may:
- Lack essential minerals like calcium and magnesium.
- Taste flat or bland due to mineral absence.
- Leach metals like lead or copper from pipes, increasing health risk.
What is the Ideal or Acceptable TDS Level in Drinking Water?
Different agencies have set varying standards for TDS in potable water:
✅ WHO Guidelines
The World Health Organization (WHO) offers a taste-based classification:
| TDS Level (mg/L) | Water Quality |
|---|---|
| <300 | Excellent |
| 300–600 | Good |
| 600–900 | Fair |
| 900–1200 | Poor |
| >1200 | Unacceptable |
While WHO has no health-based limit, it warns against high levels above 1000–1200 mg/L due to taste and possible contamination concerns.
✅ BIS Guidelines (India)
The Bureau of Indian Standards (BIS) under IS 10500 recommends:
- Desirable limit: 500 mg/L
- Maximum permissible limit (in absence of alternative source): 2000 mg/L
This range takes into account regional variations and groundwater conditions in India.
✅ US EPA Standard
The Environmental Protection Agency (EPA) in the U.S. considers 500 mg/L of TDS as the Secondary Maximum Contaminant Level (SMCL) — not enforceable by law but advised for taste, odor, and corrosion control.
What Causes TDS in Drinking Water?
Understanding the sources of TDS helps manage it effectively.
🔹 Natural Causes
- Groundwater seepage: Minerals like calcium, magnesium, and iron naturally dissolve from rocks and soil.
- Rain and snowmelt: Can carry dissolved atmospheric gases and particles into surface water.
🔹 Human Activities
- Industrial discharge: Chemicals and salts from factories increase TDS.
- Agricultural runoff: Fertilizers and pesticides contribute nitrates and phosphates.
- Urban sewage: Leaching from sewage lines or poorly managed waste adds to TDS.
How to Measure TDS in Water?
🔸 Digital TDS Meter
- Quick & Portable
- Insert the device into water — it gives instant readings in ppm.
- Ideal for homes, field testing, and RO systems.
🔸 Conductivity-Based Measurement
- TDS correlates with electrical conductivity (EC).
- Conductivity (µS/cm) is multiplied by a factor (typically 0.65–0.75) to estimate TDS.
🔸 Laboratory Gravimetric Method
- Most accurate but time-consuming.
- Involves evaporating a known water sample and weighing the residue.
Effects of TDS on Water Quality and Appliances
💧 Taste and Odor
- TDS >500 mg/L may cause salty, bitter, or metallic taste.
- Low TDS water (<100 mg/L) may taste flat or demineralized.
⚙ Impact on Plumbing and Appliances
- High TDS, especially calcium and magnesium, leads to scaling in:
- Pipes
- Water heaters
- Dishwashers
- Washing machines
- Scale reduces efficiency, increases energy use, and requires frequent maintenance.
How to Reduce TDS in Drinking Water?
Choosing the right water treatment method depends on your water source and TDS level.
1. Reverse Osmosis (RO)
- Best for TDS >500 mg/L
- Pushes water through a semi-permeable membrane.
- Removes 95–99% of TDS and contaminants.
- Ideal for:
- Borewell water
- Industrial water
- High-salinity areas
⚠ Note: Water may require remineralization post-treatment.
2. Distillation
- Water is boiled → steam is condensed → minerals are left behind.
- Produces ultra-pure water.
- Slow and energy-intensive.
3. Deionization (DI) / Ion Exchange
- Exchanges calcium and magnesium ions with hydrogen/sodium.
- Common in water softeners.
- Doesn’t remove other impurities like bacteria or nitrates.
4. Electrodeionization (EDI)
- Combines RO and ion-exchange with electrical current.
- Produces ultrapure water for pharmaceuticals or electronics.
5. Blending / Dilution
- Mix high-TDS water with low-TDS water.
- Used in areas where RO isn’t feasible.
- Helps adjust TDS to within acceptable range.
TDS Levels and Suitability for Usage
| TDS Range (mg/L) | Suitability |
|---|---|
| 0–50 | Ultrapure water (labs/industrial) |
| 50–150 | RO water, suitable for short-term drinking |
| 150–300 | Ideal for regular human consumption |
| 300–500 | Acceptable, may have taste variation |
| 500–1000 | Tolerable; filter if possible |
| 1000–2000 | Not ideal; needs treatment before drinking |
| >2000 | Unsafe for consumption |
Special Considerations Based on Demographics
👶 Infants and Elderly
- Require water with balanced mineral content.
- Low TDS can cause mineral deficiency.
- High sodium or nitrate levels in water are risky for babies.
🚰 People with Kidney Disease or Hypertension
- Should avoid high TDS, especially sodium-rich water.
- RO-treated water or low-sodium softeners are recommended.
Why Monitoring TDS Regularly is Important?
- Detect early contamination.
- Evaluate performance of filtration systems.
- Maintain compliance with municipal or BIS standards.
- Protect health and prevent long-term damage to appliances.
Conclusion
So, what is the acceptable TDS level in drinking water? The consensus among health agencies and experts points to an ideal range of 150–500 mg/L. This level ensures that water contains the necessary minerals without affecting taste, safety, or appliance efficiency.
Whether you’re sourcing groundwater, municipal supply, or RO-treated water, monitoring and maintaining TDS levels is essential. Use digital TDS meters regularly and choose the appropriate filtration method to achieve the optimal range.
Need Help?
If you’re unsure about the TDS level in your water or looking for advanced filtration systems, ROSP (RO Service Point) is here to assist.
✅ Residential & Commercial Water Treatment
✅ RO Systems | Softeners | Deionizers | Industrial Filtration
✅ TDS Testing & Water Quality Consultation
📞 Call: +91-6262629090
📧 Email: info@roservicepoint.com
