Booster pump on City water line

[fayazdin1]

Hi friends,
I never done this before but now I have to ………………

I have to install a pump on a city water line to pull water and pump into underground water tank. I know it is illegal in many countries but in other countries, there is no other choice because the city water pressure is very low.

Anyhow, discharge head is 50-ft. I don’t know how to calculate suction pressure because during winter, 4” city water line has water pressure (10-psi) but during summer the water pressure goes very low and sometime it is so low that water only trickles.

Can you folks shed some light on how to size pump for this application

Sincerely,
Fayaz Din

 

[steamdog]

You size the pump on the lowest water pressure available. You put a pressure control (or VFD) on the outlet of the pump so that it does not get over pressure. We use many booster pumps here in NYC for taller buildings, taking city water on the suction and discharge at a fixed pressure.

If you have no suction pressure, you cannot pump and must have a pressure switch on the pump inlet that will shut them off so they won't run dry. There is no magic, you cannot 'suck' water out of a pipe, you have to have that inlet pressure that will supply water to the eye of the impeller.

 

[bimr]

If the city water supply has inadequate pressure/flow, you may overpump the city's water supply.

1. Low water pressure may cause cavitation of your new water pump leading to premature failure of the pump; and/or

2. Contaminant your water supply by pulling in contaminants from ground water surronding the city's buried water supply pipeline; and

3. Possibly collapse the city water main.

You probably should contact the city public works engineer and obtain guidance from him on how to proceed.

If there is no water pressure, then the pump will not work and you have just wasted your money.

It would probably be more prudent to draw water when the water main has pressure and then store the water in a tank for later use (when the city water pressure is too low).