The valve in the toilet is the one to worry about. If you have more then 60 pounds, the valve might allow water to pass through it. This could be very slight, or it could be fairly steady. It's not enough to hear it running, or know it's happening. You usually find out when you get your water bill and it's something crazy like 30,000 gallons for the month, even when nobody is living there. The house this happened to me was at the bottom of a hill and the pressure was just over 100 pounds. I had no idea until I got the water bill!!!!