Rusted metal pipes in the bathroom: when replacement is overdue

How surface rust differs from a pinhole leak

Surface rust on galvanised steel usually shows as a dry, reddish-brown coating or light flaking on the outside of the pipe, often where the zinc coating has worn off at a joint, a bracket, or a spot that gets damp from condensation. It looks rough but the pipe wall underneath is still sound, and it can sit like that for years.

Pinhole leaks are different: they come from corrosion working through from the inside, and by the time you see a wet patch, a green-white mineral crust, or a drip, the pipe wall at that point has already been eaten through. The stain is often damp to the touch or slightly weeping even when no tap is running.

A useful check is to run a dry cloth or a bit of kitchen roll over the suspect area and leave it for an hour. If it comes back damp, or if the pipe feels cool and slightly wet rather than just dusty with rust, treat it as active corrosion rather than cosmetic surface rust.

What to check before deciding anything

Start by looking at the whole visible run of pipe, not just the one obvious stain, since galvanised pipe corrodes at a fairly even rate and one weak spot often means others nearby. Check joints and elbows particularly closely, as threaded fittings corrode faster than straight pipe.

Feel for dampness at floor level below the pipe, inside the cabinet under a basin, and around any tiled boxing, since a slow leak can travel along the pipe before it drips visibly. If the pipe is boxed in or tiled over, look for a damp patch, a change in grout colour, or a musty smell nearby rather than expecting to see the pipe itself.

Note how old the installation looks and whether it has been touched before. A pipe with a mix of old galvanised sections and newer copper or plastic repairs suggests someone has already been patching failures piecemeal, which is worth mentioning if you call a plumber out.

• Run a dry cloth over the stained area and check it again after an hour
• Inspect every visible joint and elbow, not just the obvious rust patch
• Check the cabinet floor and skirting below the pipe for dampness
• Look for discoloured grout or a musty smell near boxed-in or tiled pipework
• Note whether the pipe has already been part-replaced with copper or plastic

What is dangerous and needs quick action

Any active drip, weeping joint, or damp patch that is getting bigger over days rather than staying the same size needs attention soon, because a pinhole in steel pipe rarely seals itself and tends to widen. Water tracking into a floor void, a downstairs ceiling, or a shared wall in an apartment building can cause damage well beyond the pipe itself and, in a block of flats, affect a neighbour's flat.

If you see rust-coloured water when you first open a tap after it has stood unused for a while, that on its own is not an emergency, but combined with a visible wet patch nearby it points to a pipe close to failing. Treat that combination as urgent rather than something to watch for another month.

If a leak is already active, shutting off the isolation valve to that fixture, or the stopcock if there is no local valve, stops the damage while you arrange a plumber. Abimeister is on call around the clock for urgent jobs like this in Tallinn and Harju county.

What can reasonably wait

Dry, flaky surface rust with no dampness anywhere nearby, particularly on a pipe in a well-ventilated spot, can usually wait until it suits you to have it dealt with alongside other bathroom work. There is no need to book an urgent call-out for something that has clearly been stable for a long time.

The same goes for cosmetic staining on a pipe that is otherwise sound, for example a mark left by an old drip that has since been fixed, or light rust bloom around a bracket where the zinc coating was scratched during installation. Cleaning and repainting that section, or having it looked at during a routine plumbing visit, is enough.

If you are planning to retile the bathroom anyway, it is worth having a plumber check any pipework that will be boxed in again before the tiler starts, so a slow-developing problem is not sealed behind new tiles for another decade.

How this differs from replacing the building's main riser

The riser is the shared vertical pipework running through the building from the basement to each flat, and its condition, age and replacement is normally a decision for the apartment association, not something one owner arranges alone. That is a separate, larger question covered elsewhere.

This guide is about the visible supply pipes inside your own bathroom, the short runs feeding the basin, bath, shower or toilet cistern, which you as the owner or tenant can usually have replaced independently of what happens to the riser. Replacing a fixture supply pipe does not require agreement from the whole building.

If you find corrosion on the riser itself, for example where it passes through your bathroom before branching off, that is worth flagging to the apartment association alongside dealing with your own fixture pipework, since the two are connected but decided separately.

What replacement costs and how the work goes

For a straightforward job, such as replacing one or two rusted supply pipes with copper or plastic, a plumber can usually assess it on site and give you an hourly estimate rather than a fixed quote, since the scope is often visible once the old pipe is exposed. Plumbing work with Abimeister starts from 45 € per hour, with a minimum of one hour and 30-minute steps after that.

If the pipe is boxed in or tiled, opening it up, replacing the pipe, and closing it again is more work, and it is often worth pricing that alongside any tiling that needs doing regardless, since tiling work starts from 35 € per job. Doing both at once avoids opening the same section of wall twice.

Once the new pipe is in, it is covered by a 24-month guarantee on the work itself. The old galvanised pipe is not repaired or patched, since a patched section next to unreplaced pipe of the same age will usually fail again nearby before long.