water gushes

Hi, In our loft, we have two tanks - a small header tank for the central heating and a larger tank for the hot water - cold water is mains fed. The other night, we noticed that the overflow pipe from the hot water tank was dripping outside. I was looking out of the window to see how much was...

This has been going on intermittently for some time, but now is almost every time a cold water tap in the house is turned on. Water bursts out of the tap in stop start gushes, accompanied by quite loud gugg, gugg, noises that are not the banging pipes noises described by some members. It takes...