Was woken in the night by a loud noise, I thought someone was digging up my driveway with a pneumatic drill. Was surprised to find it was the hot tap on the basin in our en suite making all the noise. As I adjusted the handle of the tap the noise changed, decreased, increased..... luckily there was an isolation valve in the pipe so I fetched a screwdriver and was able to go back to sleep. It now vibrates constantly, sometimes loud, sometimes not so loud. What causes this? No other tap in the house does it and, as I say, turning it off at the valve stops it, so I'm assuming its a fault in the tap. But I've never come across it before.