The past week I have noticed that when I open the hot water tap to run a bath, the pressure of the water coming out the tap is much weaker than normal (if I have to give a % as to what it used to be I would say from 100% down to 40%). Then if I turn the cold water tap on while the hot water is still running, the hot water tap then goes to even more weaker pressure (now to say 20%), and also the pressure of the cold water tap is also less as to what it used to be normally. I have a pressure valve geyser, and first thought that comes to mind is the pressure valve. I last had the pressure valve replaced 4 years ago.
Please advise anyone.