House music

SIR – I wonder if readers can throw light on a baffling conundrum.

For several months now I have heard a low-level humming noise in my house. It gets progressively louder at night (and when the weather is humid) and sounds like someone blowing down a piece of metal pipe.

Possible culprits – the electrics, boiler or Wi-fi – have all been discounted. I am currently exploring the possibility that it may be due to either a breached water main or a problem with the gas meter/pipes. Kim Halliday

Newport, Essex