Free tool
Which purifier do I need?
Answer a few questions about your actual problem and get a straight recommendation — including, where it applies, the recommendation not to buy anything yet.
What are you trying to solve?
Air and water problems have nothing in common except the word 'purifier', so this is the only fork that matters first.
How this tool thinks
Almost every purifier recommendation online starts from the product and works backwards. This one starts from the problem, because the most expensive mistakes in this category are not choosing the wrong model — they are buying the wrong category of machine entirely.
The two classic errors run in opposite directions. Over-buying is by far the more common: households on treated municipal supply below 200 ppm running reverse osmosis, paying more upfront, more every year, discarding two to three litres for every litre they drink, and stripping out calcium and magnesium to solve a problem that was never there. Under-buying is rarer but far more serious: a UV purifier on borewell water in a fluoride or arsenic belt looks and feels like protection while providing precisely none against the contaminant that matters.
So the water branch asks about source before anything else, and sends anyone on borewell supply to a laboratory test rather than to a product page. A TDS meter cannot distinguish harmless calcium from arsenic — that single limitation is responsible for more misplaced confidence than any other fact in this industry.
The air branch works the same way. It asks what you are actually trying to remove, because HEPA does nothing whatsoever for gases and odours and carbon does nothing for particulate, and then it asks how big the room is, because a purifier that cannot turn over the air in the space it is in will disappoint you regardless of its badge.
Every answer this tool can give
Published in full, so you can read the reasoning without working through the questions — and so that none of the advice is hidden behind an interaction.
Do this first — no purchase yet
Start by measuring, not by shopping.
If you cannot name the problem yet, no purifier recommendation is going to be meaningful. Two cheap measurements will tell you far more than any amount of reading.
For water, a TDS meter costs around ₹300 and tells you in thirty seconds whether you need RO at all — a very large number of Indian households run RO on supply that never needed it.
For air, check your local AQI over a week and see whether indoor levels track it. If your city runs clean most of the year, a purifier for the two bad months is a different purchase from one running continuously.
Recommendation
You need HEPA and a substantial activated-carbon stage — carbon is the part most cheap purifiers skimp on.
Smoke is two problems in one. The particulate fraction is handled by any decent HEPA filter. The gaseous fraction — the part you can actually smell — is only handled by activated carbon, and the thin carbon-impregnated mesh fitted to budget units is largely decorative against real smoke loads.
Look for a unit with a genuine carbon stage measured in hundreds of grams, not a coating. Then check what that carbon filter costs to replace and how often, because against continuous smoke it will saturate faster than the HEPA.
Size it generously. Smoke episodes are exactly when you need the machine to turn the room over quickly, and a unit running flat out at its rated limit will neither keep up nor let you sleep.
Important: If the smoke is from indoor tobacco, no purifier removes the risk to other occupants — it reduces the smell and the particulate, which is not the same thing.
Important: Carbon filters saturate silently and can begin re-releasing odours. Replace on schedule rather than on smell.
Recommendation
A purifier with a real activated-carbon stage will handle this, but extraction at the source will do more.
For cooking odours in particular, a working kitchen chimney or exhaust fan removes the load before it reaches the rest of the home. A purifier is cleaning up after a problem that extraction prevents, and it is the more expensive way round.
Where extraction is not possible, or for occasional sources like paint and solvents, activated carbon is the relevant technology. HEPA does nothing whatsoever for gases and odours — this is the most common misunderstanding in the category.
Do this first — no purchase yet
Find the source first. A constant smell is usually damp, mould or drainage, and filtering it forever costs more than fixing it once.
A purifier running continuously against a constant odour source is an expensive way to treat a symptom. Carbon filters saturate under that load in months rather than years, and the running cost mounts up quickly.
Damp and mould smells in particular indicate moisture that will keep causing problems — including to the building — long after you have masked the smell. A dehumidifier and a repair are the actual answer.
Once the source is dealt with, reassess. You may find you do not need a purifier at all, or that you need a much smaller one than you were about to buy.
Recommendation
A unit of roughly 200–250 m³/h CADR is right, and quiet operation matters more than headline CADR here.
A bedroom is the highest-value room to purify, because you spend eight uninterrupted hours in it with the door shut — which is exactly the condition a purifier needs to work well.
Check the noise figure at the speed you will actually run, not the sleep-mode number in the brochure. A unit that is only quiet on a setting that barely moves air is not a quiet purifier; it is a slow one.
Run it hard for half an hour before bed with the door closed, then drop to a low speed to hold the level. That pattern gets far better results than leaving it on sleep mode all night.
Recommendation
You need roughly 300–400 m³/h CADR — and be honest about whether the room is really closed.
Living rooms are harder than bedrooms because doors open constantly and they often connect to a kitchen or balcony. Every opening resets the work the purifier has done.
Size for the connected volume rather than the floor area of the room itself. If the living room opens onto a dining area, that is one space as far as air is concerned.
Because these units run at higher speeds for longer, filter running cost matters more here than anywhere else. Check the five-year cost before the purchase price.
Recommendation
Buy two or three well-sized units rather than one large one.
This is the most common and most expensive air-purifier mistake. Air does not circulate between rooms anywhere near well enough for a single large unit to serve a flat, so the money spent on a flagship machine buys clean air in one room and very little elsewhere.
Two mid-sized units in the two rooms you actually occupy will outperform one premium unit in the hallway, usually for less money and always for lower filter cost.
For genuinely open-plan spaces above about 500 sq ft, place units at opposite ends rather than clustering them, and treat any connected kitchen as part of the same volume.
Do this first — no purchase yet
Measure it before you buy. A ₹300 TDS meter decides between a ₹2,800 purifier and a ₹34,000 one.
This is the single highest-return thirty seconds in the whole purchase. Buying without measuring is how households end up running RO on 120 ppm municipal supply — paying more upfront, more every year, discarding thousands of litres and stripping out calcium and magnesium to solve a problem that was not there.
Test at more than one time of year if your supply blends municipal and borewell water. Seasonal swings of 300–500 ppm are entirely normal in much of India, and a summer reading can imply a very different machine from a monsoon one.
In the meantime, your city's indicative range is a reasonable starting point — but treat it as a starting point, not a measurement.
Recommendation
You do not need RO. UV + UF will disinfect this water without stripping it, for less money and no waste water.
Below 200 ppm there is nothing meaningful for reverse osmosis to remove. RO here costs more to buy, more to run, discards two to three litres for every litre it purifies, and takes out calcium and magnesium you actually wanted.
What this water may still need is disinfection, and that is what UV and UF are for — they deal with bacteria, viruses and cysts without touching dissolved minerals.
If a salesperson tells you that you need RO on 150 ppm supply, that is a commission talking. Take the win.
Important: One exception overrides the TDS reading entirely: if your area has documented arsenic, fluoride or nitrate contamination, you need RO regardless of how low the TDS is. UV and UF remove nothing dissolved.
Recommendation
Either technology works. RO with a TDS controller if you want the flexibility; UV + UF if you want the cheaper, water-efficient option.
This is the genuine grey zone, and anyone who tells you there is only one right answer is selling something. At 200–500 ppm the water is not objectively unsafe on TDS grounds, but it may taste hard or leave scale.
If you go RO, insist on a TDS controller and have it set to deliver 50–150 ppm at the tap. Driving output to near-zero is a waste of the minerals and of the membrane.
If taste is acceptable and you have no specific contamination concern, UV + UF is the more economical choice and produces no reject water at all.
Recommendation
You need RO, and you need a membrane rated well above your actual TDS rather than just above it.
Above 500 ppm reverse osmosis is doing real work, and this is the case the technology exists for. The decision now is specification rather than technology.
Check the membrane's rated maximum input TDS against your worst-season reading, not your best. A membrane rated to 2,000 ppm fed 2,200 ppm water in summer will not fail dramatically — it will simply die early and quietly, and you will replace it annually.
Above 1,500 ppm, get a laboratory analysis before buying. At those levels the specific ions matter, and a bulk TDS figure will not tell you whether you are dealing with hardness, salinity or something that needs dedicated pre-treatment.
Important: High TDS usually means hard water too. Without a softener upstream, membranes scale and their life collapses — budget for that rather than discovering it.
Do this first — no purchase yet
Get a laboratory test before you buy anything. Borewell water is the one case where a TDS meter is genuinely not enough.
TDS is a bulk measure. It cannot distinguish harmless calcium from arsenic, fluoride or nitrate, and groundwater across large parts of India carries exactly those. Water reading a comfortable 250 ppm can contain arsenic well above the permissible limit and look perfectly reassuring on a meter.
If you are in West Bengal, Bihar, Assam, eastern Uttar Pradesh, Rajasthan or Punjab, this is not a precaution — those are documented contamination belts and a NABL-accredited test is the responsible first step.
Once you have the report, the technology choice usually becomes obvious. RO handles dissolved contamination; specific problems like high iron or heavy hardness need dedicated pre-treatment ahead of it.
Important: Do not let a TDS reading alone reassure you on borewell supply. That is the specific mistake this page exists to prevent.
Recommendation
Assume variability and specify for the worst delivery, not the average one.
Tanker supply is the least predictable input in Indian domestic water. The source changes between deliveries, and so does everything about the water — TDS readings varying by several hundred ppm between loads are common.
That variability is the specification. Choose a membrane rated comfortably above the highest reading you have seen, not the typical one, because the machine has to cope with the bad weeks.
Tank hygiene matters more here than on piped supply. Have your storage tank cleaned on a schedule — a purifier downstream of a contaminated tank is solving the problem in the wrong order.
The questions it asks
- What are you trying to solve?
- What is the main air problem?
- Is the smell constant, or does it come and go with an activity?
- How big is the room you want to clean?
- Where does your water come from?
- Do you know your water's TDS?
Go deeper
- TDS calculator
- Room size → CADR calculator
- The purifier database
- Something already broken?
- RO vs UV vs UF
- Air purifier buying guide