I recently had a home inspection done on my house and I was told that our water pressure was 90psi and to lower it. I purchased a water pressure gauge and tested and confirmed 90psi. I adjusted the water pressure regulator by adjusting the screw then retested. The gauge started at 50 psi but slowly continued to climb back to 90psi. I tested the pressure in the house and it began strong but after only a few seconds was definitely noticeably lower. I guess my question is what is my true psi? Is it resting in the pipes at 90 until initial pressure is released? Is the regulator possibly bad? Any tips/ advice is much appreciated

Would like a few more opinions on this. Recently had my gas hot water heater replaced, (50 gal Bradford-White). When I asked the plumber how often I should do a drain/flush maintenance, he told me "it is not necessary. The newer units are pretty self sufficient." The drain spout on the new water heater did not have a turn valve, just a set type screw. Also asked about wrapping it with an insulation blanket, as the previous one had it. Again, not necessary. Water Heater is located in a primarily finished basement. Heat is only turned on when necessary. Rarely goes below 58 degrees in the winter. BTW, this is a reputable plumbing company that I've used a few times with no issues. However, I believe this guy was new.