Old house, 1948, city water.
I have regulator on main set to 50psi

We had a problem when washer runs it's impossible to take shower. But recently (last 3 month or so) it became worse. If you take shower and someone flushes toilet water flow in a shower almost goes to the 0.

I have central filter system, so I replaced filters at first, no help.
Then I opened bypass valve (on filter which I have to temporary reroute cold when changing filter) - same thing.

Then I adjusted regulator to 70 psi. Now I get more pressure but once something else uses water - it drops. It almost feels like "not enough volume" if that is correct term.

It's not specific to any of the faucets, not specific to hot or cold. It almost feels like not enough "path through" for more than one recipient.

I ask neighbor and his pressure seem to be OK. He said maybe in a morning when people run sprinklers he would see lower pressures. But other than that - OK

When measuring and all recipient shut - 70psi
When opening kitchen faucet - pressure drops to 40psi
When washer filling up - pressure drops to 20psi

Any suggestions on what that should mean? Bad regulator? When washer running I can hear "hiss" where main comes in to house, so definitely some restriction going on.

[![enter image description here](https://i.stack.imgur.com/f8Y98.jpg)](https://i.stack.imgur.com/f8Y98.jpg)