I'm glad I shared these thoughts with all of you. I've decided to
reexamine everything. I know there is an end cap on a pipe on the side
of the house where I notice the reduction. It began to drip and I
discovered that the "professional, licensed, plumber" I had rearrange a
few pipes about 30 years ago used a zinc end cap rather than all copper.
It's corroding. I cut into another one about a year ago when it started
to drip and found a tremendous amount of black mush inside. This may be
my root cause.

Also learned from this exercise is that no one seems to find fault with
the idea of purging the system with pure vinegar. And, "No", I'm not a
chef. Vinegar is the least expensive "acid" that will dissolve mineral
deposits and leave a system whole.

Thanks to all of you for taking time to offer your ideas and comments.

On 5/19/2011 3:50 PM, RogerT wrote:
jaygreg wrote:
Here's how I led to the speculation:

1) White mineral deposits formed at end of faucet nozzles (lightly but
enough to find material in the screen filters... usually
white...assumed calcium)

2) Water pressure noticeably lower. Neighbors notice no change in
their pressure.

First, regarding your original post -- I think that is an interesting idea
although I really don't know whether it would work or not etc.

But, since you said that you have all copper plumbing, as others have
said -- it doesn't appear that corrosion would be the reason for a lower
water pressure/flow.

Since you wrote earlier that you are finding the low flow problem "in
selected pipes", it may just be that dirt and particles of debris are
clogging the faucet aerator screens etc. If you did any plumbing work
(repairing valves etc.), pieces of dirt and debris can break loose and clog
the screens. Happens all the time. The same could be true if the town did
some work on water lines outside of your house.

Another possibility could be a valve which has a rubber washer that is
broken or damaged or came off from the valve stem. If that happens, opening
the valve can still leave the washer stuck in the valve in a position where
it restricts the water flow. This could be in a main water valve or another
valve somewhere else. You would have to take the valve stem off and look to
be sure.