Diagnostics
Purifier problems, diagnosed properly
Symptom-led troubleshooting for water and air purifiers. Every cause comes with a way to confirm it before you spend anything — because replacing a ₹2,500 membrane to fix a ₹250 sediment filter is the most expensive mistake in this category.
Water purifiers
RO and water purifier problems
Taste, flow, TDS, leaks, noise and service indicators.
Your RO water tastes bad — here is how to find out why
In most cases it is an exhausted activated-carbon filter — a ₹200-450 part that is the single most common cause of taste and odour complaints, and one that many households never replace because the machine keeps running without it.
6 possible causes · 2 you can fix yourself
Your RO tank is not filling — work through it in this order
Start with inlet pressure and the sediment filter. Between them they account for most cases, and both are cheap — a choked sediment filter is a ₹150-350 part, and low supply pressure costs nothing to confirm.
6 possible causes · 1 you can fix yourself
Your RO is dispensing slowly — the usual causes, in order
If the tank is full but water dispenses in a dribble, the problem is usually the tank rather than the filters. If the tank itself fills slowly, work through the pre-filters first.
5 possible causes · 3 you can fix yourself
Your RO output TDS has gone up — what that actually means
Measure input and output TDS together and calculate the rejection rate. A healthy domestic membrane rejects roughly 90-95% — if yours still does, the membrane is fine and something else has changed.
5 possible causes · 2 you can fix yourself
Your RO output TDS is very low — when that matters
Below about 50 ppm you are drinking near-demineralised water: it tastes flat, and you have discarded the calcium and magnesium your supply was giving you for free. It is a taste and nutrition question rather than an acute safety one, and it is usually correctable without new hardware.
3 possible causes · 1 you can fix yourself
Your RO is sending too much water down the drain
Some reject water is physics, not a fault — the membrane needs cross-flow to stay clean. But 1:3 recovery is poor by current standards, and low inlet pressure or a scaling membrane will push it far worse than it needs to be.
5 possible causes · 1 you can fix yourself
Your RO purifier is leaking — find the source before anything else
Most domestic RO leaks come from a filter-housing O-ring that was not seated properly at the last service, or from a push-fit connector that was disturbed. Both are cheap. A cracked housing or a failed tank is not.
5 possible causes · 3 you can fix yourself
Your RO purifier is making a noise — what each sound tells you
A pump hum during filling is normal. Hammering, rattling or a machine that never falls silent is not — and continuous running is the one to act on quickly, because it wastes water and shortens membrane life.
6 possible causes · 2 you can fix yourself
Your purifier's filter light is blinking — what it is actually telling you
On most domestic purifiers the filter light is driven by a timer or a litre counter, not by a sensor measuring filter condition. It tells you the scheduled interval has elapsed — which may or may not mean your filters are actually spent.
4 possible causes · 3 you can fix yourself
Air purifiers
Air purifier problems
Weak PM2.5 reduction, noise, smells, sensors and filters.
Your air purifier is not bringing PM2.5 down
The commonest reason is not a fault at all — it is that the unit is too small for the room, or the room is not closed. A purifier rated for 350 sq ft cannot hold down a 600 sq ft open-plan living area with a door to the balcony open.
6 possible causes · 6 you can fix yourself
Your air purifier has become noisy
If the noise appeared suddenly, it is usually something loose or something in the fan. If it has grown gradually, it is more likely a loading filter making the fan work harder, or bearings starting to wear.
6 possible causes · 5 you can fix yourself
Your air purifier is producing a smell
A musty smell is a saturated carbon filter or damp media and needs a filter change. A burning or hot-plastic smell is electrical and means switch it off at once.
5 possible causes · 4 you can fix yourself
Your air purifier's filter has turned black
A blackening filter is the unit doing its job — that material would otherwise be in your lungs. It is only a problem if it happens far faster than expected, which points at your environment rather than the machine.
4 possible causes · 4 you can fix yourself
Your air purifier's light will not turn green
First establish whether the light is reporting air quality or filter life — they are different indicators and people routinely confuse them. If it is air quality, a dirty optical sensor is the most common cause of a light that never goes green.
5 possible causes · 4 you can fix yourself
Your air purifier's readings do not look right
Consumer optical sensors are indicators, not instruments. They are useful for trend and direction, and they should not be treated as calibrated measurements — especially not the ones sitting in the purifier's own clean-air outlet.
4 possible causes · 4 you can fix yourself
Your air purifier's fan will not run
If it powers up but does not blow, check the front panel is fully latched — most purifiers have a safety interlock that silently prevents the fan running when the panel is not seated. That is the single most common cause and it costs nothing.
5 possible causes · 4 you can fix yourself
How to use these guides
Start from what you can observe, not from what you suspect. Purifier troubleshooting goes wrong when someone decides the membrane has failed and then buys a membrane — the symptom that sent them there was often a choked ₹250 pre-filter, and the new membrane will choke behind it just as fast.
Each guide lists causes in order of how often they turn out to be responsible, with a check for each one. Some of those checks cost nothing and take a minute: measuring input and output TDS before condemning a membrane, timing a one-litre fill before blaming the pump, latching a front panel before declaring an air purifier dead.
Where a job genuinely needs a technician, the guide says so and explains what to ask for. Mains electricity in a cabinet full of plumbing, UV lamps and pressure vessels are not places to experiment, and a page that pretends otherwise is doing its reader no favours.