Condensation on rising main or a leak?

Avoriaz

Hi, as you can see from the picture our 22mm copper rising main comes vertically up inside the kitchen undersink cupboard via a stopc0ck, pressure limiting valve, a horizontal 15mm tee to kitchen cold water tap and dishwasher and then disappears via a hole in the rear of the cupboard to the rest of the house.

The 15mm horizontal pipe at the top is the hot water feed to the sink.

During the recent hot spell I noticed that the rising main pipe was wet and some water had dripped off onto the cupboard floor. Putting a dry tissue through the hole in the rear of the cupboard where the rising main disappears shows that the pipe was slightly wet in there too.

Hoping that it was simply condensation from warm humid air on a very cold rising main, I dried all the pipework. I couldn’t find any leak in the visible pipework.

Water reappeared the next day but, on the third day, when the weather had cooled and was less humid, it remained dry. It has warmed up again and the pipe is very slightly wet again.

I am 95% certain, and 100% hopeful, that it is just condensation and not a leak somewhere, as a leak beyond the cupboard would be a major job to locate and remedy. The house was built in 2004.

Is that type of condensation normal and how do I prevent it or limit its future impact?

I plan considerable replumbing under the sink as I am installing a water softener in there.

Would plastic pipe to replace the copper help? The pipe below the stopc0ck is plastic.

Can I clad the rising main in insulation or a water absorbing cover?

Your comments and advice will be appreciated.

*j*

As you suggest, Avoriaz, it's condensation. Cold water (from being underground) in the pipe and a warm kitchen.

You could put pipe insulation around the pipe. This would reduce the condensation if it prevented the warm air reaching the pipe, but the best thing is that you wouldn't be able to see it !

*j*