If you've ever tested your water or looked at an RO purifier brochure, you've probably seen the term TDS. But what does it actually mean? Is low TDS always better? And how do you know if your water's TDS is safe for your family to drink every day?
In this guide, we'll explain everything about TDS in plain language — no jargon, just clear facts you can act on.
What is TDS?
TDS stands for Total Dissolved Solids. It measures the total concentration of dissolved substances in water — including minerals, salts, metals, and other compounds.
These dissolved solids can include things like calcium, magnesium, sodium, potassium, bicarbonates, chlorides, and sulphates — some of which are naturally present and even beneficial, while others (like heavy metals or excess nitrates) can be harmful.
💡 Simple way to think about it: TDS is like a measure of "what's swimming in your water besides water itself." Some of it is good (minerals), some neutral, and some potentially harmful.
How is TDS Measured?
TDS is measured in milligrams per litre (mg/L) or parts per million (ppm) — they mean the same thing for practical purposes.
A simple TDS meter (a small pen-like device) can test your water in seconds. Our CaresureRO technicians carry TDS meters and will test your water for free when they visit your home.
What TDS Level is Safe for Drinking?
| TDS Level (ppm) | Water Quality | Suitable for Drinking? |
|---|---|---|
| 0 – 50 | Very low | Safe but may taste flat — lacks minerals |
| 50 – 150 | Ideal ✓ | Best range for drinking water |
| 150 – 300 | Good ✓ | Acceptable and safe |
| 300 – 500 | Fair | Acceptable but may taste slightly salty |
| 500 – 900 | High ⚠️ | Not recommended for long-term use |
| 900+ | Very High ✗ | Not suitable for drinking |
The WHO (World Health Organisation) recommends TDS below 300 ppm for drinking water. The Bureau of Indian Standards (BIS) sets the acceptable limit at 500 ppm and the desirable limit at 300 ppm.
Why is My Water's TDS High?
Several factors can raise TDS in your water supply:
- Natural minerals — water picks up minerals from rocks and soil as it flows underground
- Old pipes — corroding pipes can leach metals like lead and copper into the water
- Agricultural runoff — fertilisers and pesticides can enter groundwater
- Industrial discharge — in urban areas, industrial pollutants can raise TDS
- Seawater intrusion — in coastal areas, salt can enter the groundwater table
How Does an RO Purifier Reduce TDS?
A Reverse Osmosis (RO) purifier forces water through a semi-permeable membrane with pores so tiny (0.0001 microns) that dissolved salts, heavy metals, and most contaminants simply cannot pass through.
A good RO purifier can reduce TDS by 80–95%. So if your tap water has a TDS of 600 ppm, your purified water could come out at 30–120 ppm — right in the ideal range.
🧪 Not sure what your water's TDS is? CaresureRO offers a free water test at your home anywhere in Hyderabad — with zero obligation to purchase. Book your free test →
The Bottom Line
TDS is one of the most useful indicators of water quality — but it's not the only one. Water with low TDS can still contain bacteria or viruses, which is why a good purifier uses RO + UV + UF filtration together.
The ideal TDS for drinking water is between 50–150 ppm. If your water is above 300 ppm, an RO purifier is worth considering — and we'd be happy to help you find the right one for your home and budget.
Get a Free Water Test at Your Home
Our expert visits, tests your TDS and water quality on the spot — completely free, no obligation.
🧪 Book Free Water Test