WS,

What flow rate and pressure are you proposing your pump to produce. The pressure difference in the barrels will be very small. Here is a link to low pressure switches.

http://www.mamcoswitches.com/pressure-switches.html

Good luck and aloha

I would like the same rate and flow as my house, I think it's 40~50 psi with~6gpm. the rain barrels produce very little, more like a trickle. QUESTION: I read, I may need a pressure tank(bladder), so the pump doesn't cycle on and off as i turn the spray nozzle on and off every time. This is for water about12-16 different area's, maybe set up a lawn sprinkler to water grass. Thanks Joe

WS,

What square footage are the 12-16 different areas and the total of all the areas? The pressure is good for irrigation heads and sprinklers. At 5 gpm you you will empty your barrels in 33 minutes. Will you be hand watering with a hose? Will you refill your barrels by hose for the next cycle of irrigation? How big is your lawn? Aloha