Jerome your question is a little hard to decipher and your spelling is horrific
I'm going to give it a shot:
A municipal water system is a (closed water system) and it is under
pressure. That is how the water is delivered to you home. Since the
pressure is greater than atmospheric, when you open the faucet, the
water flows.
But one can argue the wording because for water to flow it has to draw air from somewhere which typically is the vent on top of a water tower.
In our area you have to take out a permit for water heaters and install it to todays code which includes expansion tanks. I'm not sure about electric water heaters though?
Not sure what you mean by this (and or do they had relief at a common area anywhere?)
