Rain water bouncing off nearly-horizontal and diagonal external pipes onto brickwork Drainage and wastage systems and plumbing help, advice and answers

[Mark Lawrence]

I live in a ground floor flat in an Edwardian end-of-terrace property. My upstairs neighbour's waste bath and washbasin water flows through external plastic pipes into a hopper in a downpipe, and then into a drain. My own bathwater and washbasin water flows through a similar configuration of plastic pipes into the same drain. During heavy rain, I have noticed that water splashes off the top of the pipes onto the brickwork, which I believe has caused damp to penetrate through the masonry and manifest itself on internal plasterwork. My upstairs neighbour also has internal damp patches roughly corresponding to the external location of his pipe runs. I am reluctant to paint the external wall with any sort of barrier paint, so that the brickwork is still able to "breathe" during dry weather. Suggestions to prevent the rainwater splashing of the pipework greatly appreciated.