SPRINKLER TALK FORUM - You Got Questions, We've Got Answers

Your shallow well pump will do okay, but for a good sprinkler system on a shallow well pump, don't use too small a pipe diameter. You have little enough pressure to begin with, and you want to make an extra effort to avoid pressure losses.

I am with WetBoots, make sure you use a large enough diameter pipe because of your lower pressure.

Is this your pump? http://www.sears.com/sr/javasr/product.do?BV_UseBVCookie=Yes&vertical=LAWN&pid=08302522000&tab=spe#tablink
Note that you already need a 20 amp circuit for the pump. A good cast-iron-case 3/4 HP shallow well pump could outperform that Craftsman 1HP on that page. That being said, you could get by with 10 gpm for half an acre. Most shallow well pumps will deliver more water at a lower pressure, so you might consider the implications of a 30 psi water supply - Right now, I'm looking at an old catalog, showing a 3/4 HP high-capacity cast iron pump that delivers (ten foot suction lift) 11 gpm at 40 psi, and 30 gpm at 30 psi. Unfortunately, to make best use of a pump like that, I would need a mainline pipe size of at least 1 1/2 inches. (and an equally large suction pipe - no well points can be counted on for 30 gpm) As for sprinklers that work at less than 30 psi, there are only two types I've worked with that could handle such low pressures. (Rainbird's R-50 ball-drive rotor, and their Maxipaw impact heads) - the R-50 is about as good as it gets, once you figure out the adjustments, and accept the shorter spray distances you get at less than 30 psi. The Maxipaw is less reliable, but capable of long life, and is especially good for pumping 'dirty' pond water.

Save your money. Those are toys compared to the real thing. The higher the pump has to lift the water, the less flow and pressure you will get. Consider just working with the 10 gpm at 40 psi. It is adequate for the job, unless your soil is pure sand.

The 'jet' is for coaxing higher pressure (or higher lift) from a pump. For deep well use, there would be two pipes running from the pump to the well, and the injector assembly (containing the jet) would be located down below the water level in the well. The pump pushes some water down into the well, through the injector assembly, which allows the pump to bring up water from much deeper than a shallow-well pump can.

I personally wouldn't buy those pumps off Ebay. Most everything on there of that sort is cheaply made and probably won't last you more than a couple years. Invest in a high quality durable pump.