It sounds like you may have problems with your city water. I have looked at water filters for some time now, and I've found some great deals out there. The reason I think it's you city water is because it takes a lot of material to clog a filter or supply line. There's not much that exists in a pipe (in your house) that would erode away and clog the system later on in the flow. I would suggest seriously looking at one of those large water filters. 50-100 gallons or so; if not more. I think I saw a vendor with good pricing on them at http://www.caraudiovideosystems.com
I believe the manufacturer was Water RX or something like that. I just picked up one of the smaller units, but I just wanted it to insure I'm drinking pure water, and not all the chemicals that have been found in drinking water lately.