I cannot figure out this pulsing/thumping in my water line. It can be felt on the incoming line from the house and make niose at the hot water heater. Can be stopped if I turn a shut off valve before the hot water heater. Before the shut off it splits to other portions of the house such as tiolets and faucets. It isn't constant but goes for 20-30 seconds then off for a minute. I already closed all the tiolets shut off valves at the tiolet and it still thumps. I have a 40 gal. water heater w/ expansion tank, no backflow preventor or regulator, city water and 85 psi pressure. Driving me nuts.

Pressure way to high. Reduce to no more than 60 lbs,40 or 50 would be better.

A lot of water meters make a thumping sound when water is flowing. Is it stronger by the meter?

Yes you can feel it after meter but stops when I shut the water before the hot water heater, it spits in other places before there so it has other places it is not shut off. And this is when no water is running in the house. You can feel the pulse in the pipes all over. Never constant. Its not the 'water meter sound' when water is flowing I no that sound. This is a soft thump that is felt in the pipe and heard.

Do you have the pulsing/thumping all the time or just when water heating is heating? Do you have a pressure regulating valve. Pressure is to high.

No pressure regulator. I turned the power off to heater and makes no difference. And for some reason its not all the time, maybe a minute or two between when it happens then goes for maybe 20-30 secondes.

Any sign that the T&P valve on the water heater may be releasing. Regardless of what is causing the vibration/noise, you need to install pressure regulating valve and reduce the pressure.

T an p valve good. You guess regulator is on the to do list.

I think it's simple enough. It sounds either like a pop or roar that lasts maybe 20 seconds or so. The key is, it stops when you turn off the water to the hot water heater. It doesn't matter if it's electrically off or not.

It's overdue to remove the sediment from the tank. Occaisonaly bad things happen when it hasn't been done for a while like the sediment clogs the drain valve or the sediment passing scratches the seat of the drain.

Monthly, you should open the drain valve on the water heater and drain the sediment until it runs clear.

The problem is, you may effectively have rocks in your water heater because that's what the noise sounds like.

Another place that makes pulsing/thumping noises would actually be the main shut off seat or the cold water shut off to the hot water heater. Usually these noises occur at specific flow rates. Increasing or decreasing the water flow will make it stop.
Also, in order for that noise to happen the pipes are probably not secure.

Interesting, couple months ago I checked the water pressure and it was at 70 psi and didn't notice my annoying thump/pulse, township apparently boosted the water pressure and didn't let anyone know, that would explain why my flexible washer lines blew.

Yep, pressure regulator is on the to do list.