Water Purifier Buying Guide for India (2026)

The right purifier follows your water, not the brand's advert. So the first job is to know what is in your water. Two very different problems drive the choice.

• Germs — bacteria and viruses. Common in untreated or stored water. Handled by UV or UF.
• Dissolved salts (high TDS) — plus metals like arsenic or fluoride. Common in borewell water. Handled only by RO.

This matters a lot. In its 2025 report, the CGWB found 28.3% of groundwater samples failed the BIS limit on at least one measure. Nitrate, fluoride and arsenic are all common.

Who most likely needs RO:

• Borewell or tanker users — TDS is often high and variable.
• High-TDS regions — parts of Rajasthan, Haryana, Delhi-NCR and other belts.
• Homes with metal contamination — arsenic, fluoride or high nitrate.

If your supply is treated municipal water with low TDS, you may not need RO at all. A UV or UF unit could be enough. Figures from CGWB and BIS (see Sources).

TDS means Total Dissolved Solids. It is the weight of dissolved salts and minerals in water, in mg/L. It is the single most useful number for choosing a purifier.

But a TDS meter has limits. It cannot see bacteria. It cannot flag a specific metal like lead or arsenic. For those, you need a lab test.

BIS drinking-water limits (IS 10500:2012)

India's standard sets two tiers. The acceptable limit is the target. The permissible limit applies only when there is no better source.

A 2015 amendment cut arsenic to 0.01 mg/L. Limits from BIS IS 10500 (see Sources).

Municipal vs borewell

• Treated municipal supply — usually lower and steadier in TDS. Often chlorinated.
• Borewell or tanker water — usually higher and more variable. The main reason people buy RO.

How to check your own water

• Digital TDS meter (₹200–500) — fast. But it reads only salts, not germs or metals.
• Lab test (₹500–2,000) — the gold standard for metals and bacteria. Worth doing yearly.
• Ask your utility — request its water quality report and source.

One fact drives the whole decision. UV and UF deal with germs. RO deals with dissolved salts. Neither UV nor UF reduces TDS or removes heavy metals.

RO — Reverse Osmosis

A pump forces water through a very fine membrane. Its pores are about 0.0001 micron. It rejects over 99% of dissolved salts, plus heavy metals and fluoride.

• Best for — high-TDS water above about 500 mg/L, or water with metals.
• Needs — electricity, decent pressure, and it wastes some water.

UV — Ultraviolet

A UV lamp disrupts the DNA of microbes. It inactivates bacteria and viruses. It does not remove TDS, metals or the dead cells.

• Best for — low-TDS municipal water where the only worry is germs.
• Needs — electricity and reasonably clear water.

UF — Ultrafiltration

A membrane with 0.01 to 0.1 micron pores sieves out germs and dirt. It works on water pressure alone. It lets dissolved minerals pass, so it does not cut TDS.

• Best for — low-TDS water, or homes with unreliable power.
• Needs — no electricity to run.

The supporting stages

• Sediment filter — traps dirt, rust and silt. Protects the parts downstream.
• Activated carbon — removes chlorine, odour and organic chemicals.
• TDS controller — blends some original minerals back into RO water.
• Mineraliser — a cartridge that adds minerals back after RO.
• Water softener — a separate device for whole-house scale, not for drinking.

This is where buyers spend the most time. Work it in order. Test your TDS. Check for germs or metals. Then match the technology.

A rough map by input TDS

The 500 mg/L line is the BIS limit. The finer cut-offs are market convention, not a standard.

Do not over-purify

Lower TDS is not always better. This is the part most buyers miss. The WHO warns against water with too little mineral content.

• The WHO puts the optimum drinking-water TDS at about 250 to 500 mg/L.
• Water below 50 to 75 mg/L tastes flat and corrodes plumbing.
• It also leaches calcium and magnesium from the body over time.

So do not chase a near-zero reading. If your RO output is very low, use a mineraliser or a TDS controller to bring it back up.

The rule India nearly made law

The National Green Tribunal directed a curb on RO where source TDS is below 500 mg/L. Its reason was mineral loss and water waste. But the Supreme Court stayed that order in 2022.

So RO is not banned below 500 mg/L. The sound advice still stands. Below that level, RO adds little and wastes water.

Most buyer time goes here, so it is worth the detail. RO works against natural pressure, so it needs a pump and power. It is also slow. That is why it stores water in a tank.

A typical stage stack

The order varies by model. Not every unit has all of these. A common stack runs like this.

1. Sediment filter — dirt, rust and silt.
2. Pre-carbon — chlorine and odour. Protects the membrane.
3. RO membrane — the core. Removes salts, metals and fluoride.
4. Post-carbon — polishes taste.
5. UV or UF — an extra germ barrier.
6. Mineraliser or TDS controller — restores minerals and taste.

Membrane GPD and tank size

• GPD — Gallons Per Day, the membrane's rated output. Common home ratings are 50, 75 and 100 GPD.
• Real output — often only half to three-quarters of the rating. It depends on pressure and TDS.
• Storage tank — usually 5 to 10 litres. It gives instant water and a buffer during power cuts.

TDS controller vs mineraliser

• TDS controller — bypasses a little water around the membrane. Cheap, no consumable. Weak where metals are present.
• Mineraliser — adds minerals after full RO. Safer and steadier, but a consumable to replace.

Booster pump and pressure

RO needs enough inlet pressure to work. Most Indian homes on overhead tanks fall short. So domestic RO units ship with a built-in booster pump. Good pressure also cuts water waste.

Filter and membrane life

One key point. Overdue pre-filters are the top cause of early membrane failure. Grit and chlorine then reach the membrane and wear it out. Prices are indicative; verify on the live Amazon.in page.

RO removes well:

• Dissolved salts, so it cuts high TDS.
• Heavy metals like arsenic and lead, plus fluoride and nitrate.
• Hardness, as a side effect, at that one tap.

UV and UF remove germs, but not:

• Dissolved salts. They do not lower TDS at all.
• Heavy metals or fluoride. These pass straight through.

So germs and dissolved solids are two separate problems. Match the tool to the real problem in your water.

Two specs work together here. Tank capacity is how much water is stored. Purification rate is how fast the unit makes it.

• Daily need — a family of four uses about 8 to 12 litres of drinking and cooking water.
• Storage tank — 9 to 12 litres suits most families of three or four. Step up for larger homes.
• Purification rate — home units run about 12 to 15 litres per hour.

Storage matters most where power or water supply is patchy. A full tank buys you a buffer. A higher rate helps high-use homes refill faster.

The Indian mark to check is the BIS standard mark to IS 16240. This standard covers RO-based home purifiers.

It is now effectively required for RO units. Rules notified in 2023 make the standard mark mandatory on domestic RO purifiers. So look for it on the box.

NSF and WQA are global marks. They are a bonus, not a legal need in India.

Filters and service are the real cost, not power. A purifier draws only 25 to 60 watts. That is roughly 150 to 800 rupees a year.

The AMC (annual service plan)

• Service-only — about ₹1,000 to ₹3,000 a year. Parts are billed extra.
• Comprehensive — about ₹3,000 to ₹7,000 a year. It includes at least some parts.
• Total spend — budget ₹4,000 to ₹10,000 a year with consumables.

Read the fine print. "Comprehensive" is not standard. Some plans leave out the RO membrane. Confirm in writing what is covered.

Water wastage

RO wastes water by design. A home unit wastes about 3 litres for every 1 litre it cleans. The reject water is salty, so do not drink it.

• Good reuse — mopping floors, washing vehicles, cleaning, toilet flushing.
• Avoid — salt-sensitive plants. The salt builds up in the soil.

Service network matters

A purifier is only as good as the technician who can reach you. Filters need regular swaps. So check that the brand services your area before you buy.

• "Everyone needs RO." False for low-TDS municipal water. UV or UF is the right fit there.
• "Lower TDS is always better." False. The WHO warns against very low-mineral water.
• "Alkaline water has proven benefits." Reviews find the health claims are not supported.
• "Copper water is a health upgrade." It is tradition. Broad wellness claims are unproven.
• Skipping filter changes. A neglected unit can grow bacteria and pollute your water.
• Buying before testing. Test input TDS first. It decides whether you need RO at all.

1. Test your input TDS. Add a lab test if you use borewell water.
2. Match the technology. RO for high TDS, UV or UF for germs.
3. Do not over-purify. Aim for a TDS around 250 to 500 mg/L.
4. Size the tank to your family and your power supply.
5. Look for the BIS mark to IS 16240 on the box.
6. Cost the filters and the AMC, not just the sticker price.
7. Confirm the brand services your area before you buy.

This guide draws on standards and health bodies, government data, manufacturer documentation, and established publications.

• IS 10500:2012 — Drinking Water Specification (TDS, hardness, contaminant limits) — Bureau of Indian Standards
• Product Manual for IS 16240 — RO-based Point-of-Use water treatment systems — Bureau of Indian Standards
• Water Purification System (Regulation of Use) Rules, 2023 (IS 16240 standard mark) — Ministry of Environment, Forest & Climate Change
• Annual Ground Water Quality Report 2025 (nitrate, fluoride, arsenic, salinity) — Central Ground Water Board
• Groundwater contamination across India — CGWB report analysis — Mongabay India
• Total Dissolved Solids in Drinking-water (palatability, no health-based limit) — World Health Organization
• Health Risks from Drinking Demineralised Water (minimum TDS, remineralisation) — World Health Organization
• NGT directive on RO purifiers where TDS is below 500 mg/L — India Water Portal
• Supreme Court stays NGT ban on RO purifiers below 500 mg/L TDS — Business Standard
• Standards for water treatment systems (NSF/ANSI 42, 53, 58, 401, P231) — NSF
• Product certification and the Gold Seal mark — Water Quality Association
• UF & RO: a technical overview (pore size, rejection, water recovery) — Ecologix Environmental Systems
• Water purifier buying guide (independent consumer body) — Consumer Voice
• Alkaline water and health — evidence review (claims not supported) — Frontiers in Medicine
• A.O. Smith completes acquisition of Pureit from Hindustan Unilever — Business Standard

Related guides & reviews

More on clean, safe water and other home essentials.

• All Water reviews & guides →
• Best RO Water Purifiers in India 2026 →
• Best Water Dispensers in India 2026 →
• All Buying Guides →