Hello. This is an ongoing problem. Three or four months ago, I had low cold water pressure in half the house. A couple guys came and blew out the water lines from every valve. The water pressure from the well spigots outside was fine. When they were done, things were fine. Then, the water pressure in the house started getting low, again, until the shower was just a trickle. Still, the outside well spigots are fine. Today, I had friends come and replace the hot water heater, but before they hooked it up, we blew the lines, again, with a 120 psi compressor. Now, the cold water starts with good pressure but then it slowly dwindles. I'm so frustrated! Takes forever to shower and I have to use the hose to fill the wash machine! Someone said it's the pressure in the well tank. Wouldn't that affect the well spigots outside, too? They seem to still be fine. Do you think the pvc water lines need replaced? It's a 15 year old mobile home.