Why is the water pink?

[PinkyPinkyPink]

We have a guest bathroom that isn't used very much and when I first run the water it is pink. Hot pink. Not rusty coloured. A plumber has had a look and is baffled. Google only talks about issues at supply level which it isn't as doesn't affect anywhere else. The plumber said the water is at mains pressure. Any ideas? I'm worried it's dangerous.

No idea, but we have had pink 'mould' growing in our bathroom before. Could it be this??

might be old red rubber washers in taps. They perish with age. Easily replaced.

Is your plumber youthful?

Thanks for the suggestions. Could the mould be inside the pipes?

The bathroom is in the extension which was built about ten years ago, is that the right sort of time for rubber washers? The plumber must be in his early 30s, not especially youthful is it?

I don't remember people using red rubber washers for many years, since modern plastic tapwashers have been around. IIRC they had better heat resistance than black rubber. You occasionally see them in old taps, or in a tobacco tin in a granddad's shed.

I don't think they would have been used in an old stopcock.

Sometimes people add coloured dyes to trace leaks (the colour will show up where the leak is). I usually suggest food colouring which is harmless and not permanent, but there are special fluorescent dyes for the job. They will glow under a UV light.

If you care enough, you can work out where it's coming from by trying various taps along the route, it must be between the last clean tap and the first red one. If you have compression joints a plumber can undo them to see what colour comes out. I think I might start by taking the taps off, looking inside them, and running some water out of their pipes.

I get pink marks around the toilet and bath where the water drips a couple of days after cleaning them - apparently it’s to do with the iron content in the water. Could it be something like that settling in the water that sits in the pipes?

I think that limescale, with a pink mould living on it. Wouldn't happen in pipes.

come to think of it, if the taps are fed from a cold water tank in the loft, that is seldom used, it is possible for bacteria or possibly fungus to grow in it. I have seen in in a neglected old feed and expansion tanks for radiators, never in a tapwater tank, but I suppose it is possible. I've used water-purifying chlorinating tablets to prevent it, but the tank needs to be drained, scrubbed out and wiped with bleach (including the lid and ballcock) when it happens. A tight fitting lid and an insulating jacket usually prevent it.

You will not get growth in a hot-water cylinder because the temperature is high enough to pasteurise it and kill bacteria. Copper pipes and cylinders are also thought to be slightly antibacterial.

I don't think there is a tank and the plumber said it was mains pressure. There is a shower in the same room that doesn't run pink. Never seen it in any of the other taps either. It is very odd.

Is it really pink or is it light/colour reflected from somewhere else?

It is definitely very pink. It runs clear again after a minute or so