I have had extremely poor water pressure. So poor, only dribbles of water come out. So what I did was this. While the shower was turned on, I went outside and I turned the mains off and then turned it back on and all this water blasted out of the shower head. However, when I turn off the shower and then turn it back on, the pressure goes back to none existent. But when I repeat the same process of turning shower on and shouting off the mains, etc, I get awesome water pressure and it stays great as long as I don't turn the shower off. What could be the reason?

Hi Cad78

How is the water pressure at all other fixtures in the home? In other words, is this issue isolated to the shower valve or are all plumbing fixtures in the home involved?

Back to you...

Mark

Sounds like your pressure is just fine but your volume drops way to low. I would disassemble the shower valve. I could tell you how if you could tell us the brand and model, is it a single handle?