Before you touch anything
Water and a mains adapter share the cabinet, so the order matters more than the fix.
- Switch off at the wall socket and unplug. Not the purifier's own switch; the plug.
- Close the inlet tap on the supply line.
- Open the purifier's tap until the flow stops, so the housings are no longer under pressure.
- Look at the adapter. If it is wet, or was sitting in the water, do not plug it back in at all. That is a technician's call, and the installation checklist explains why it should never have been on the cabinet floor.
- Dry everything with a cloth, lay a sheet of newspaper or paper towel under the machine, then open the inlet, plug in and watch for ten minutes.
Water runs downhill, so the wet patch is always below the leak, never at it. The paper shows you where the first drop lands; follow it upward with a dry finger and you will find the joint. Do this once and you skip most of the guessing below.
The five places an RO leaks
| Where | What you see | Usual cause | Fix | Who |
|---|---|---|---|---|
| Housing cap | Weep from the thread, worse after a cartridge change | O-ring displaced, dry or pinched; cap cross-threaded | Reseat the O-ring, refit hand-tight | You |
| Push-fit connector | A bead of water at a tube collar | Tube not pushed home, cut at an angle, or scored | Trim and re-insert, once | You, one try |
| Pre-filter bowl | Wet bowl with the cap tight; a hairline you can feel | Cracked bowl from over-tightening or age | New bowl kit ₹499 or two-candle kit ₹899 | You |
| Tank fitting or float | Water under the tank or from its lid | Loose tank connection; float valve stuck open | Reseat the fitting; the float is a technician's part | Technician if float |
| Membrane vessel or pump | Spray or steady drip from the vessel or the pump head | Vessel cap seal, cracked vessel, pump gasket | Diagnosis under pressure | Technician |
Housing O-rings: the five-minute fix
Most leaks arrive the day after a cartridge change, and most of those are the O-ring. Each housing seals not on its thread but on a rubber ring in a groove in the cap; the thread only squeezes it. When the cap comes off, the ring can lift out of its groove, twist, pick up a grain of grit, or dry out. Screw the cap back on with the ring out of place and the thread tightens but the joint weeps.
With the pressure released and the machine unplugged, take the cap off again. Lift the ring out, wipe it and the groove clean, and look at it: a flat spot, a nick or a hard, glossy surface means it has had its life, and a new one is a few rupees from any hardware shop. Seat it flat in the groove, and if you have food-grade silicone grease, a thin smear helps it seal; never petroleum jelly or oil, which swell the rubber. Screw the cap on hand-tight plus a quarter turn. A spanner pulled hard is how bowls crack, which is the section below.
If the cap will not go on square, look at the cartridge. A cartridge a few millimetres too long for the housing holds the cap off its seat, and the joint leaks however the O-ring sits. That is the fit problem the Branded-Fit vs Universal-Fit guide exists for: the Branded-Fit and Universal-Fit sediment cartridges are the same media at the same ₹190 with different ends, and only one of them seals in your housing.
Push-fit connectors: one careful try
The quarter-inch tubes on a purifier press into collet fittings. The tube has to be cut square, pushed past the collet's teeth to the stop inside, and left straight. A tube cut on a slant, pushed in only as far as the teeth, or scored along its side where it was pulled out before, seals on the day and weeps once the pump has pressed on it for a week.
With the pressure off, hold the collar in, pull the tube out, and cut off the last centimetre square with a sharp blade. Push it back until it stops, then tug to check it has locked. Restore pressure and watch. If it still weeps, stop. The fitting's teeth or its internal seal are damaged, and a second and third attempt scores the tube further and makes the fitting worse; the service vs DIY guide puts persistent push-fit leaks on the technician side for exactly that reason, and a new fitting is a few rupees plus the visit.
Cracked bowls: replace, never repair
A hairline crack in a clear housing or the wall-mounted pre-filter bowl is easy to miss and impossible to fix. It comes from a spanner pulled too hard, from a bowl tightened cold and then warmed by the sun, or simply from years of pressure cycles. Under pump pressure it opens a little wider each time the pump starts, so a bowl that only dampens today sprays next month. Tape, glue and sealant do not hold on a pressurised vessel and leave a joint that fails without warning; if you can feel the crack with a fingernail, the bowl is finished.
For the wall-mounted pre-filter, the replacement is the whole housing and it arrives complete. The LUX-PFH-10 bowl kit at ₹499 is the threaded-cap bowl with a 9-inch candle, elbow, pipe and spanner. The LUX-PFK-2C at ₹899 is the plain-cap bowl with two 10-inch spun candles, elbows, spanner and pipe, for silty water. Both are Universal-Fit with quarter-inch push-fit ports; the housing sizes guide explains the difference. The housings inside the purifier are specific to its make and are not a LUXGEN part; that is an order to the purifier's own maker, and usually a technician's visit, because the housing carries the push-fit ports and the bracket with it.
The tank fitting, and the float
Water under the tank has two sources. The tube into the tank's fitting is a push-fit like any other and is treated the same way: one careful re-seat. The float valve inside a gravity tank is different. It closes the feed when the tank is full, and a float stuck open means the tank overflows through its lid, quietly, onto whatever is below it, which in a badly installed machine is the adapter. If the water is coming from the lid rather than the fitting, the float is the cause. It is part of the control chain that the tank not filling guide explains, where the same float stuck the other way stops the tank filling at all. It is a make-specific part at a few hundred rupees, and the same visit that fits it should check why it stuck.
Membrane vessel, pump, and when to stop
The membrane vessel and the pump are the two parts of the purifier that carry full pump pressure, up to 140 PSI behind a pump such as the LUX-PUMP-100. A steady drip from the vessel's cap or a spray from the pump head is not a homeowner job: the cap seal, a cracked vessel and a pump gasket look alike from the outside, and a hairline crack under that pressure opens without warning. A membrane that has been leaking at its own end caps is the one case where the part is a LUXGEN one, since the molded membrane has no glued seams to leak from, but the vessel around it is still the technician's call.
Stop and call when the leak is at the membrane vessel or the pump, when water has reached the adapter or the UV lamp connector, when a push-fit still weeps after one re-seat, or when the paper test cannot find the source. The visit is a few hundred rupees and varies by city; the part, if it is the pump, is ₹1,299. Turn the machine off at the wall and close the inlet until someone comes. A dry cabinet is worth more than a day without the purifier.
Questions
Why is my RO purifier leaking after a filter change?
Almost always the housing O-ring. It lifts out of its groove, twists or picks up grit when the cap comes off, and the thread tightens over it without sealing. Unplug the machine, close the inlet, release the pressure, take the cap off, seat the ring flat in its groove and refit hand-tight plus a quarter turn. A cartridge of the wrong fit holding the cap off its seat causes the same leak.
Can I fix an RO leak myself?
Housing O-rings, push-fit connectors and a cracked pre-filter bowl are yours, with the machine unplugged and the inlet closed first. A push-fit gets one careful re-seat; a cracked bowl is replaced, never taped. The membrane vessel, the pump, the float valve and anything near the adapter or the UV lamp are a technician's job.
Is a leaking RO purifier dangerous?
It can be, because the mains adapter and the UV lamp connector share the cabinet with the water. Switch off at the wall and unplug before touching anything, and if the adapter is wet, do not plug it back in. A small weep from a housing is a nuisance; water reaching an electrical part is a reason to stop using the machine until it is checked.