On 21 Apr 2006 10:06:24 -0700, wrote:

Since last week every time someone takes a bath the T&P valve
discharges a small amount of water. When this happens, the water looks
a bit rusty. If I pull lever on the valve, the rusty water will drain
and for a day or so there'll be no more leaks, then it starts again. I
checked the water line pressure and it's at 60 PSI.

I've replaced the valve and flushed the tank for about 30 min - two
days later the leak is back and water is rusty again when the lever is
pulled.
Any ideas?

Try draining and flushing the hot-water tank, (that should
take care of the rust for a while) and then making sure
that the expansion tank (which should be on or near the
water tank) is not full of water. Can you have someone
run the tub while you watch the valve, to see if it leaks
while the water's running, or when they shut if off, or
at some other time?