Why does my water pressure build up after I turn the faucet off. I have about 2 seconds of high water pressure when I first turn on a faucet, any faucet in my house. This just started happening yesterday. After the 2 second surge, the water pressure returns to the normal level. I am on city water and do not have a well or pump at my house. Any ideas?

Do you know the city water pressure is in your neighborhood and also if you have a pressure reducing vale (PRV.)

Yes, I do have a PRV valve where my main enters the house. I do not know what the city water pressure is.
THANKS

I have also noticed that my toilet fill valve does not shut off completely. (you can still hear a very slight amount of water seeping past the valve) This stops when I open a faucet and relieve some pressure.

Yes, I do have a PRV valve where my main enters the house. I do not not know what the city water pressure is.
THANKS
Call the Water Department and ask them what the pressure is out in the city main. You should install a 100PSI gage close to the PRV valve so you can monitor your house pressure. It should be around 45 PSI. It sounds like your PRV valve may be going bad, but you really need to know how much house pressure you have got. From your complaint I have a hunch it's too high. Regards, Tom

I agree, the PRV is likely failing. That toilet ballcock is telling you it can't hold back the excessive pressure.