How to choose a water purifier: RO, UV or gravity?
The right purifier depends on what is in your water. An RO purifier on low-TDS municipal water wastes water and removes useful minerals. A UV purifier on salty borewell water does nothing for the salt. Test first, then choose.
As an Amazon Associate we earn from qualifying purchases. Product links open Amazon.in. Prices and availability are shown on Amazon.
Step 1: test your water
Check TDS with a meter at the very least. Better still, get a drinking water test (IS 10500) that also covers bacteria, hardness, iron, nitrate and, for borewells, arsenic and fluoride. The result tells you which technology you need.
Konvio Neer Digital TDS Meter
Quick check of total dissolved solids in tap, borewell, RO and packaged water. Handy for seeing when RO filters need changing.
Lab note: Measures dissolved salts only. It cannot detect bacteria, arsenic, lead or pesticides.
Check price on AmazonHigh TDS, hard or borewell water: RO + UV
If TDS is above about 500 ppm, or the water is hard or brackish, choose RO. Most RO purifiers also include UV or UF for germs. Expect some reject water. Many models now recover part of it.
Aquaguard Delight Aquasaver RO+UV+UF+MC
For high-TDS borewell or tanker water, where dissolved salts need to come down.
Lab note: RO is not needed if your water TDS is already low; check TDS before buying.
Check price on AmazonUrban Company Native M1 Water Purifier
RO purifier with a long filter-service interval, for households on hard or high-TDS water.
Lab note: Ask for the installer to set TDS output to a sensible level rather than the lowest possible.
Check price on AmazonLow TDS municipal water: UV + UF
If TDS is already low (typical of treated municipal supply) and the concern is germs from tanks and pipelines, a UV + UF purifier is enough and wastes no water.
Aquaguard Sure Delight UV+UF
For municipal or low-TDS water where the main concern is germs, not dissolved salts. Wastes no water.
Lab note: UV does not remove dissolved salts, fluoride or arsenic.
Check price on AmazonNo electricity or a tight budget: gravity
Gravity purifiers suit treated municipal water and homes with frequent power cuts. They are not suitable for high-TDS or chemically contaminated water.
Pureit Classic 23 L Gravity Purifier
Budget option for treated municipal water and homes with frequent power cuts.
Lab note: Not suitable for high-TDS or chemically contaminated water.
Check price on AmazonMaintenance: filters and sediment
Change filters on schedule. A rising TDS reading at the purifier outlet is the easiest sign that the RO membrane is due. A tap sediment cloth shows how much rust and silt is coming through your pipes.
Apec Complete RO Service Kit (with copper alkaline filter)
Full set of replacement cartridges for common domestic RO units, for doing the filter change yourself.
Lab note: Check the cartridge sizes match your purifier model before ordering.
Check price on AmazonUniversal Faucet Filter Cotton (pack of 20)
Catches rust, sand and sediment at the kitchen or bathroom tap; shows at a glance how dirty the supply is.
Lab note: A sediment cloth does not make water safe to drink.
Check price on AmazonCommon questions
Do I need RO for Kolkata municipal water?
Often not. Treated municipal water usually has low TDS, so UV + UF is typically enough. Borewell and tanker water is different, so test it first.
Does RO remove arsenic and fluoride?
A good RO membrane reduces most dissolved contaminants, including arsenic and fluoride, but you should confirm with a laboratory test of the purified water.
How do I know my purifier is still working?
Check output TDS monthly, and get a microbiological test (coliform and E. coli) of the purified water once or twice a year.
Need a definite answer?
Home kits and purifiers are no substitute for a laboratory report. We test drinking water to IS 10500 and food to FSSAI standards, with sample pickup across Kolkata.