I bought and am remodeling a 30 year old house in Ca. when I took one of the shut off valves off in one bath the pipe was brownish color on the inside. We are on a well. What does this mean, should I be concerned ? water appears clear at tap. I am putting all new valves and fixtures in and if I should somehow supplement the system or change out pipes ( concrete slab ) now is the time, I am removing most all drywall to get to needed repairs. Thanks, Tim