Need info on well pump from lake up the hill...

I know little about well pumps.... customer wants me to install a pump from his boat dock on the lake to pump water up the hill for irrigating his lawn. This is a reservoir lake. The lake level varies as much as 30 ft although normal seasonal variation from spring till fall is 14 ft. Water will have to be pushed up the hill .... not sure but I'm guessing a 40 ft vertical lift until I am able to survey the change in elevation.... (this would give a total 70 ft lift possibly required if the guess is close to accurate).
Question... how much pressure should I consider for the height (or pressure per ft of height)? I am assuming that the pump should deliver 20 psi at a minimum when the lake is at it's lowest level...but would appreciate someone giving me the information to calculate the difference at various lake levels....and any good suggestions on parts to put this system together... I only have to install the pump and drop a pipe in the water to suck up the lake water... I assume I should install a foot valve and might be able to use a shallow well pump on top of a small pressure tank....maybe it's a Sears item....any info will be appreciated... I'll be checking with my plumbing supply house as well.

70 ft = 30 psi. 20 psi seems a little low for pressure to an irrigation system. I would want at least 40 psi.

You need to get the customer to tell you what he wants for GPM and pressure before you buy the pump.

If this is just something where the customer wants to connect a hose to a sprinkler, then a jet pump will do the job. If it is going to be an installed/buried irrigation system, then you definitely need to get the requirements before you pick the pump.

A jet pump will be least expensive, but a submersible will give the most range to accommodate varying pressure when the lake level drops. If a jet pump it should be as close as possible to the water elevation because greater lift will cut down the available pressure and GPM of the pump.

A shallow well jet will be the most tolerant of varying flow demand without requiring a pressure tank. You can do the same with a submersible but you will get a lot of feedback here about CSVs and tanks.

Come back with the GPM requirements and we can give you more suggestions on the pump.

Bob...thanks for the reply... I went to Speedbump's website and found the info charts of equivalents that are very helpful...figured out that each foot of height costs .433 psi of pressure loss. Other info suggests 1 gpm per fixture in a house....so coming up with a flow rate will be my next challenge. All I know so far is that this guy has invested alot of bucks in his fancy lawn turf and plants and doesn't want to lose it in the drought. I have an appointment to give him an estimate Wednesday evening. The real trick on these lake water pumps is to minimize the freezing and bursting of pipes in the winter... I just re-plumbled one last week because of the cracked PVC pipes with no insulation. All I could do to help avoid that was to install a hose pipe bibb on a tee where the pipe comes out of his tank. I'll bet that it will freeze and bust the tee on top of the pump again next winter...and I wonder about the pipe that drops down into the water.....suggestions appreciated.

Everyone that I know who pumps water out of a lake does one of two things.

1. Remove the pump and piping in the winter, or drain it where it can be drained and left in place. This works if it is just used for irrigation.

2. Bury the pipes below the frost line and protect the pump from freezing.

There are usually regulatory issues with burying pipes in the lake and making a permanent installation.

With the large swing in water elevation, I would probably plan to put a pipe in the lake, probably with a submersible pump.

Since the irrigation is to protect a big investment, I would talk to the owner to find out how he wants to use it, and put in a system that will fully meet his needs. He probably wants to hear from you what he needs, and whoever offers him a top quality system will get the job.

This is one where understanding his requirements is an essential starting point.

Just need to know how many sprinklers with GPM and pressure required by the sprinklers. I would use a submersible pump, as the 30 feet of change in the lake level could leave a jet pump not being able to draw any water. You can also install a bleeder orifice in the pipe below the freeze level. When the power is turned off to the pump and the pressure is let out of the system, the bleeder will open and drain the system to that point.