You’ve probably seen “TDS” mentioned on water purifier boxes, in your building’s water tank report, or in a salesperson’s pitch. But what does it actually mean for your family’s daily health? More importantly — what TDS level should your drinking water have?
At Nexus Water Purifier, we’ve been manufacturing ISI 16240:2023 certified RO water purifiers for years, serving homes and businesses across Asia. In this guide, our technical team breaks down TDS in simple terms — what it is, what causes it to spike in Indian cities, and exactly how to bring your water to the ideal range.
Quick Answer: The Bureau of Indian Standards (BIS) sets the permissible TDS limit at 500 mg/L. The WHO recommends below 300 mg/L. The ideal range for taste and health is 150–250 mg/L. Below 50 mg/L is considered too pure and actually lacks essential minerals.
TDS stands for Total Dissolved Solids. It measures the total amount of minerals, salts, metals, and other dissolved substances present in water — everything that has dissolved into it from its source environment.
These dissolved substances include:
TDS is measured in mg/L (milligrams per litre) or ppm (parts per million). Both units are equivalent — 1 mg/L = 1 ppm.
How TDS is Measured: A TDS meter (a simple digital pen device) measures the electrical conductivity of water. Since dissolved minerals carry electrical charge, higher TDS = higher conductivity. You can buy a TDS meter for under ₹300 online and test your water at home in 30 seconds.
TDS is a quick indicator of overall water quality, but it’s not the whole story. Here’s what it signals:
Many people assume that lower TDS = purer = better. This is a dangerous misconception. Water with TDS below 50 mg/L:
This is exactly why Nexus purifiers include a built-in TDS controller and mineral cartridge — so after RO purification removes harmful substances, the right level of essential minerals is added back in, landing your water in the ideal 150–250 mg/L range.
| TDS Level (mg/L) | Water Quality | Health Implication | Nexus Recommendation |
|---|---|---|---|
| Below 50 | Too Pure | Lacks essential minerals | Add TDS controller or Zinc/Mineral cartridge |
| 50–150 | Excellent | Ideal for children & sensitive individuals | Nexus RO with mineral retention — perfect |
| 150–300 | Very Good | Balanced minerals; great taste | Most Nexus purifiers optimally tuned for this |
| 300–500 | Acceptable | Generally safe per BIS standards | RO recommended; Nexus TDS controller to fine-tune |
| 500–900 | Poor | May cause laxative effect; scale buildup | Nexus RO essential; replace membrane every 12 months |
| 900–1200 | Very Poor | Health risk with prolonged consumption | Nexus high-capacity RO with pre-filter required |
| Above 1200 | Unacceptable | Not suitable for drinking | Commercial-grade purification needed |
Sources: Bureau of Indian Standards IS 10500:2012 | WHO Guidelines for Drinking Water Quality | Nexus Technical Team
Water quality varies dramatically across Indian cities. Here’s an overview based on available municipal data:
| City | Avg TDS Range (mg/L) | Common Source | Risk Level | Nexus Solution |
|---|---|---|---|---|
| Delhi NCR | 300–700+ | Groundwater / Yamuna | High | RO + UV + UF |
| Mumbai | 150–320 | Bhatsa Reservoir | Low–Moderate | RO or UV+UF |
| Surat | 400–800 | Ukai Dam / Groundwater | High | Nexus RO with high TDS membrane |
| Jaipur | 500–1200+ | Groundwater | Very High | Nexus heavy-duty RO essential |
| Chennai | 100–300 | Surface water | Low | RO with mineral cartridge |
| Bengaluru | 100–600 | Mixed sources | Moderate | RO recommended |
| Ahmedabad | 600–1000+ | Groundwater | High | Nexus RO + pre-filter |
Get Your Water Tested Free: Nexus Water Purifier offers a free water quality assessment for homes and businesses. Our certified technicians check TDS, pH, and microbial contamination and recommend the right purifier. WhatsApp us: +91-85954-57917
The effects of high TDS water are not immediate — they accumulate silently over months and years.
Excess dissolved calcium, oxalate, and other minerals progressively concentrate in kidney tubules. India has one of the world’s highest rates of kidney stones, and research consistently points to high TDS groundwater as a contributing factor — especially in Rajasthan, Gujarat, and Haryana where TDS frequently exceeds 1,000 mg/L.
High sodium content in water contributes to elevated blood pressure. Arsenic contamination — common in groundwater across West Bengal, Bihar, and UP — is directly linked to cardiovascular disease with long-term exposure.
Water with TDS above 900 mg/L can create an osmotic imbalance in the gut, leading to loose stools, bloating, and IBS-like symptoms — especially in children and the elderly.
Fluoride at high concentrations causes dental fluorosis — visible white or brown streaks on teeth — and in severe cases, skeletal damage. Excess fluoride occurs naturally in groundwater across 17 Indian states.
Nexus IntelX RO Purifier — Engineered for High TDS Indian Water: The IntelX model handles input TDS up to 2,000 mg/L with 7-stage purification: RO + UV + UF + TDS controller + Alkaline + Copper/Zinc cartridge options. Starting at ₹24,100. [View IntelX →]
Our purifiers don’t just reduce TDS — they optimize it. Here’s how a Nexus multi-stage purifier processes your tap water:
Optional add-on stages: Alkaline cartridge (raises pH to 7.5–8.5), Copper infusion cartridge, Zinc mineral cartridge.
Cost: ₹200–500. Dip the electrode in your water for 2–3 seconds and read the display. Your Nexus purifier output should read 150–250 mg/L.
Water above 500 mg/L typically tastes salty or metallic. However, arsenic and fluoride are tasteless at dangerous levels — never rely on taste alone.
Place water on a dark surface and let it evaporate. White mineral deposits indicate high dissolved solids. Use a TDS meter for actual numbers.
Q: What TDS level is best for drinking water in India? A: The ideal range is 150–250 mg/L for most adults. BIS permits up to 500 mg/L. WHO recommends below 300 mg/L. Water below 50 mg/L lacks essential minerals and should be avoided as a daily drinking source.
Q: Is RO water bad because it reduces TDS too much? A: Pure RO water (below 50 mg/L) can be a concern, which is why quality RO purifiers include a TDS controller. Nexus purifiers retain an optimal mineral balance — the safety of RO with the minerals your body needs.
Q: Can I use a TDS meter to know if my water is safe? A: TDS meters track mineral levels, but don’t detect bacteria, viruses, arsenic, or fluoride. For complete safety, get a professional test. Nexus offers free water quality checks.
Q: Why does my Nexus purifier show different TDS on different days? A: Input water TDS fluctuates with season, municipal supply switching, and membrane performance. This is normal. If output TDS consistently rises above 250 mg/L, schedule a service check.
Q: Is packaged drinking water always safe? A: Not necessarily. Some brands show TDS as low as 10–30 mg/L — too pure for long-term health. PET bottles also introduce microplastic contamination. A home Nexus RO purifier provides safer, more consistent quality at a fraction of the cost.
Q: What TDS does the Nexus IntelX produce? A: The IntelX is calibrated to output 150–250 mg/L from typical Indian water. The TDS controller is fine-tuned by our technician during installation based on your specific input water.
