In reply to message posted by fourth year:
It is interesting that you discount a pump as the only way to increase pressure, but then admit that the only way to get water up to a gravity tank, once its height exceeds the limit of the city pressure is to use a pump. If the gravity tank is at the limit of the city pressure, then its pressure to the system will be EXACTLY the same as if the faucet were attached to the city system. You are so interested in being pedantic that you do not think about what you are writing.
Pressure on a lot of city water mains can fluctuate a lot with in a 24 hour period.
You see there is something that is called peek demand.
During high usage times pressure can drop over 40 PSI and considering that if a person know about this kind of chronic problem they can design a means of insuring enough pressure during these times where pressure is not adequate to normally keep up to useage.
Let say street pressure during off peek times is 80 PSI now considering 80 PSI will elevate water almost 185 ft (forgetting friction losses)
Now if we had a GRAVITY fed tank 180 FT above ground that would maintain a pressure of 78 PSI now.
See Guy this was all performed using ALREADY available STREET pressure building a reserve during non demand times Simple basic plumbing design.
» This message has been edited by Lorenzo on 28 October 2001