Do you have an expansion tank? Has the tank failed (i.e., is it full of water - it should be mostly empty and full of air)? Buy yourself a gauge for about $10 and check it yourself. What is the pressure on the inlet side? Watch the pressure on the output side, especially after tanking a shower or using a bunch of hot water which will cause the WH to turn on. Hot water expands, and if there's no expansion tank, or yours has failed, it raises the pressure until the weakest thing leaks to relieve it, or if not high enough, just results in it being (momentarily until you use some water) high.
Make sure that your main water valve is fully open. and the one(s) at the WH.