Home & Electrical

Which Water Purifier Do I Need? RO, UV or UF by Water TDS

Free tool · Updated October 2, 2026 · By CouponTalk

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Quick answer

Check your water's TDS with a ₹200 TDS meter. Below 200 ppm, a UV or UV + UF purifier is enough and RO only wastes water. Between 200 and 500 ppm, UV + UF works, and RO is optional if the water tastes hard. Above 500 ppm, the BIS limit for drinking water, you need RO + UV with a mineral cartridge. Above 2,000 ppm, get the water lab-tested first.

How to use this calculator

Fill a clean glass with tap water and dip a TDS meter in it for 10 seconds.
Choose where your water comes from. Borewell and tanker water can carry hardness and germs that TDS does not show.
Enter your family size to get the tank size you need.

TDS guide

Water TDS guide, based on BIS IS 10500
TDS (ppm)	What it means	Purifier to choose
Below 200	Low TDS, usually municipal water	UV or UV + UF (no RO needed)
200–500	Within BIS acceptable limit	UV + UF; RO optional for hard taste
500–2,000	Above BIS acceptable limit	RO + UV with mineral cartridge
Above 2,000	Above BIS permissible limit	Get water lab-tested first

These are typical figures for Indian homes. Check the product spec sheet, and ask an electrician or installer before you buy or fit anything.

Frequently asked questions

What TDS is good for drinking water?

BIS IS 10500 sets 500 mg/L (ppm) as the acceptable limit for drinking water. Water between 50 and 300 ppm usually tastes best.

Is RO water bad for health?

RO removes useful minerals with the bad ones. If your TDS is already low, choose UV or UF. If you need RO, pick one with a mineral cartridge or TDS controller.

How much water does an RO purifier waste?

Most home RO purifiers reject 1 to 3 litres for every litre they purify. Collect the waste water for mopping or plants.