I've tried adding air from a portable compressure to the air tank but got no result. We have 3 sinks and a shower upstairs and get little or no pressure to anything. What can I do to fix the water pressure?

Hello
I live in a old part of a big city and the main problem we have here is old supply pipes to the house and or in the house . Make sure all your inside pipe is copper and check with the city or a plumping outfit to detail what you have the process for outside supply from the city upgrades .