The water supply pressure in Marple does seem to fluctuate quite a lot and recently seems to have been very high at night. There seem to have been several occasions when a line of houses have their overflow pipes going in the morning, presumably because a whole load of float-valve washers have failed in one night. I've also noticed one or two occasions recently when the toilet flush has gone on continuously siphoning, suggesting the cistern is filling very fast.
There is also a rather persistent water-main leak on Station Road (just above the canal) which is becoming exceedingly treacherous in the present icy weather. I don't think that high, or at least fluctuating, pressures can have done it much good.