Low pressure and rusty water: the galvanised pipe problem

If you live in a Southern Suburbs house built before the mid-1970s — much of Bergvliet, Plumstead, Wynberg, Diep River — there is a good chance some of your water still runs through galvanised steel pipe. And there is a good chance it is quietly strangling your water pressure.

What galvanised pipe does over time

Galvanised steel is protected by a zinc coating. That coating does not last forever. Once it wears through, the steel underneath corrodes — from the inside, where you cannot see it. Rust and scale build up on the pipe wall and the bore narrows, year by year, until a 20mm pipe is passing water like a 10mm one.

Because it happens slowly, most people never notice. The shower has always been like that. Until you visit a friend with copper pipes and wonder what you have been putting up with.

The three signs

Pressure that has faded over years. Not a sudden drop — a gradual one, usually worst at the taps furthest from the meter.

Discoloured water after the house has stood. Come back from a week away, open a tap and get a brownish first flush. That is rust from inside your own pipes.

Pinhole leaks that keep appearing. This is the important one. A single leak is bad luck. A second leak on the same run, within a year or two, is not bad luck — it is the pipe telling you it has reached the end.

Patch or re-pipe?

Patching a corroded galvanised line is a genuinely reasonable thing to do — once. The problem is that cutting and re-threading stresses the corroded pipe on either side of the repair, and the next failure is often a metre further down the same run. We have seen homeowners spend more on four call-outs over three years than the re-pipe would have cost at the start.

So we will show you what is actually inside the pipe, and give you both numbers: the patch, and re-piping the affected run in copper or PEX. Then you decide with the real figures in front of you, rather than a plumber simply telling you to replace everything.

You usually do not need to do the whole house

Most houses are a mix — someone re-piped the bathroom in 1998 and left the rest. We trace what is actually galvanised and re-pipe the runs that matter, rather than quoting a whole-house job you may not need. See general plumbing and leak detection.