Scott,

You have lots of good answers - save for perhaps one. Let
me suggest moving the pressure reduction valve (replace it
if it is not a good name brand one!) out to the meter, and
see if you can find a plumber with leak detection equipment
so the leak can be fixed without replacing the entire line.

Another suggestion - there is the possibility that either
local, State or Federal agencies (Like the AWWA) connected
to the "water industry" offer free services to
municipalities for evaluating leaks in water systems. If
so, perhaps if your local water board (authority,
municipality or whatever) were in need, and able to obtain
free services in this regard after your suggestion or help -
they might be grateful enough to try and persuade the agency
performing the services to check out your mom's property
"while they are in the neighborhood".

Just some thoughts... .

I hope this helps.

Scott wrote:

What is the conventional pressure range for a city water supply? The
one at my mom's house is at 110 PSI and rising, and it's causing
multiple failures in the 60-year-old pipes that were originally
installed for a 30-40 PSI deep well supply.

At this point we're incurring a lot of expenses in repairs and, now,
replacing the entire line from main to house (~200 yards). I'm just
interested in whether the water district might have some liability for
pumping the water pressure so high.

-Scott