Water stain on the ceiling or wall: where the leak usually is

Is water dripping right now, or is the stain dry

This is the first thing to establish, because it changes everything else. Press a dry tissue or your palm flat against the stain. If it comes away damp, or you can see the edge of the patch slowly spreading while you watch, water is moving through the structure right now.

Active dripping or a visibly wet, spreading patch is urgent. Water travelling through a ceiling can reach a light fitting or a socket, and plasterboard or old lath-and-plaster ceilings can sag and come down once they are saturated. If you see water actually falling, or the ceiling has started to bulge, treat it as an emergency: get a bucket underneath, if it's safe cut power to that circuit at the consumer unit, and get help the same day.

A dry, stable stain with a hard, slightly yellowed or brownish edge is a different matter. It tells you a leak happened at some point, but tells you nothing about whether it is still active. Mark the outline in pencil and check again in a few days. If it hasn't grown, you have time to investigate properly rather than react.

If you are not on the top floor: it is probably the neighbour's plumbing

In a flat that isn't directly under the roof, the most common source by far is a pipe, appliance or seal in the flat above. Estonian panel blocks route a lot of plumbing through the floor slab, and a slow leak from a toilet connection, a washing machine hose, or a bathroom floor without a proper membrane can travel sideways before it shows up as a stain well away from where it started.

The stain's position gives a rough clue. A mark below where their bathroom or kitchen sits points to plumbing; one under an outside wall with no wet room above is worth asking about separately, since it could be something else entirely, like a balcony drain.

The practical step is simply to knock and ask whether they've noticed anything: a dripping tap, a toilet that runs longer than it should, water pooling near the washing machine. Most people are glad to be told, since a slow leak costs them water and eventually damages their own floor too. If it's a shared pipe or drain, this is also something to flag to the korteriühistu, since responsibility for stack pipes usually sits with the building rather than one flat.

If you are on the top floor: roof, chimney or flat-roof drainage

On the top floor, the roof itself becomes the likely source, and the pattern of the stain often tracks the weather. A patch that appears or grows specifically during or just after rain, especially wind-driven rain, points to a roof covering, flashing, or a chimney seal that has failed somewhere above.

In blocks with a flat roof, the usual culprit is a blocked or frozen internal drain rather than a hole in the membrane itself. Water backs up on the roof surface and finds a seam or a service penetration to get through, which can show up metres away from the actual weak point.

A stain near a chimney breast that only appears in wet weather is often the chimney flashing or capping rather than the chimney itself. This is roof and building-envelope work, which sits outside plumbing and outside what we do as odd jobs; it needs a roofer, but it helps enormously to be able to tell them when the stain appears, since that narrows down where to look.

Near a bathroom wall: often just a failed silicone seal

If the damp patch is on a wall directly behind or beside a shower or bath, and there's no flat above with a bathroom in the same spot, the cause is frequently much simpler than a hidden pipe: the silicone seal around the shower tray, bath edge, or where the wall tiling meets the floor has cracked, shrunk, or lifted, and water is getting behind the tiles every time someone showers.

You can usually confirm this yourself. Run the shower for a few minutes and watch the seal line closely, or look for silicone that has gone grey, patchy, or has a visible gap you can slide a fingernail under. If the seal looks intact everywhere, the issue is more likely a pipe inside the wall, which is a different job entirely.

A failed seal is one of the cheaper problems on this list to put right. Cutting out old silicone and resealing properly is a straightforward job we do as silicone sealing, from 45 € per job, and it's worth doing at the first sign of cracking rather than waiting for a stain to appear on the other side of the wall.

Condensation: damp without any leak at all

Not every damp patch involves water coming from somewhere. Cold external walls, especially corners, behind wardrobes, or around window reveals in older buildings, can collect condensation from ordinary room humidity, particularly in winter when the temperature difference between inside and outside is largest. This shows up as a soft-edged damp area rather than a hard-rimmed stain, and it's often accompanied by a musty smell or the first spots of mould rather than a brown tide mark.

The giveaway is that it tends to appear on external walls and in poorly ventilated corners rather than under pipework, and it fluctuates with the season and with how the room is used, growing worse after cooking, drying laundry indoors, or long showers without an extractor fan running.

This is a moisture and ventilation problem rather than a leak, and it needs a different approach entirely, covered in our separate guide on damp and mould in flats. If you're not sure which you're looking at, the tissue test from the first section and the shape of the mark are usually enough to tell them apart.

What to do before you call anyone

A bit of groundwork before you pick up the phone saves time and often saves money, since a clearer description usually means a shorter visit. Note when the stain appeared, whether it's growing, and whether it correlates with rain, someone using a bathroom upstairs, or nothing in particular.

Photograph the stain now, with something for scale, so you have a record if it changes. If you can safely check the loft, the flat above, or a service duct without forcing anything open, do so, but don't cut into walls or ceilings yourself to chase a pipe.

Once you have a rough idea of the source, you'll know who to call. A suspected pipe, whether yours or the neighbour's, is plumbing work, from 45 € per hour; a failed shower seal is a same-day silicone job; general drying out, patching, and repainting once the source is fixed falls under odd jobs, from 39 € per hour.

• Water actively dripping or a ceiling that bulges: act today, cut power to the area if safe, call a plumber
• Dry stain with a hard edge, not growing: monitor for a few days before deciding
• Not top floor: ask the neighbour and, for shared pipes, notify the korteriühistu
• Top floor, stain tracks with rain: likely roof, chimney, or flat-roof drainage, needs a roofer
• Near a shower or bath, no flat above: check the silicone seal first
• Soft-edged, no hard rim, worse in winter or after showers: probably condensation, not a leak