Advice on pump setup for shallow dug well

[Ethan Brush]

I am trying to get my water system set up here and not sure which direction to go. So I have a shallow dug well that is made about 3 foot diameter circle of laid up concrete blocks. There is a precast concrete ring and cap on top. The blocks go down about 8 feet below grade. The water level comes up just about to grade. Recovery is somewhat slow so I imagine during high water usage, the level could potentially drop down 4/5/6 feet or something. This is 600 feet from the house, and a 1" line is run. Grade is about the same as the house, perhaps the water level is 10-20 feet lower than the faucets. I would much rather use a submersible pump. My house is small and I don't want a jet pump taking up room and making noise, thus I am thinking of just using a 1/2 HP submersible. I am concerned that even that is too big however seeing as there is hardly any head, and I cant find anything smaller. The other concern is I need to use a filter and UV sterilizer, due to the the shallow depth (I have had issues before). I am concerned that that high flow rate thru the UV will make it not as effective. The other option I suppose is to have a very small pump at the well feeding a cistern in the basement, and then a pressure pump after that That could have a very low flow rate making the sterilizer as effective as possible. But I am not thrilled with that idea because that puts a pressure pump inside that I have to hear and it just seems like more components and hassle. Any thoughts or ideas?

 

[Valveman]

A 1/2HP, 10 GPM pump will work. You need to add 115' of head for the 50 PSI you need when working with a 40/60 pressure switch. As long as your well can supply enough water you don't need a cistern and extra boost pump.

 

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[Reach4]

I think you are thinking the right things.
https://terrylove.com/forums/index....a-dug-well-and-adding-a-pitless-adaptor.89592 was a recent discussion.

If you have iron or manganese to remove, there are ways to do that while killing bacteria at the same time. Otherwise, your UV sounds good.

 

[Ethan Brush]

Thanks. I know the pressuep will add "head", looking at the charts it appears a typical 1/2 gpm pump will

 

[Ethan Brush]

Thanks. Looking at some performance charts for 12 GPM 1/2 HP pumps, it does appear that I will get around 15 GPM with little head and pressure. Seems like I would a UV that is rated for that worst case flow rate. OF course generally the pressure will be 40 or above, but there is initial filling, maintance etc. The charts only go down to 20 feet of head, and I might have close to zero down in the basement. Ill try to get a more accurate head figure.

 

[Reach4]

Thanks. Looking at some performance charts for 12 GPM 1/2 HP pumps, it does appear that I will get around 15 GPM with little head and pressure. Seems like I would a UV that is rated for that worst case flow rate.

You don't put the UV before the pressure tank. So whatever gpm the pump puts out, that is not really important for deciding how many gpm the UV can handle. UV often goes after the softener, but at least after the tee-off to the outside spigots, and certainly after the pressure tank. UV always goes after a 5 micron max filter, and you never have a 5 micron filter before the pressure tank.

he charts only go down to 20 feet of head, and I might have close to zero down in the basement. Ill try to get a more accurate head figure.

If you want to pump to 60 psi, you need a 140 ft head just for that. That is before any actual elevation change. Commonly you would use a 40/60 psi pressure switch. Instead of the table, you can use the graphs.

20 ft corresponds to 8.66 psi. So you could use the table, and compensate that way.

Usually a 1/2 hp 10 gpm pump would be the pump of choice for a house where your cistern or well is near ground level.

Plus, you will lose some psi to dynamic head too. Here is a 13 gpm pump:

 

[Ethan Brush]

You don't put the UV before the pressure tank. So whatever gpm the pump puts out, that is not really important for deciding how many gpm the UV can handle. UV often goes after the softener, but at least after the tee-off to the outside spigots, and certainly after the pressure tank. UV always goes after a 5 micron max filter, and you never have a 5 micron filter before the pressure tank.



If you want to pump to 60 psi, you need a 140 ft head just for that. That is before any actual elevation change. Commonly you would use a 40/60 psi pressure switch. Instead of the table, you can use the graphs.

20 ft corresponds to 8.66 psi. So you could use the table, and compensate that way.

Usually a 1/2 hp 10 gpm pump would be the pump of choice for a house where your cistern or well is near ground level.

Plus, you will lose some psi to dynamic head too. Here is a 13 gpm pump:

Ah ok, thanks. Putting the UV after the PT makes sense.

Also there is the friction loss of the pipe. I ran it through a few online calculators and the 600' alone results in about 75'

 

[Valveman]

At 10 GPM you will only loose 33' or 14 PSI in 600' of 1" PVC pipe. You might want to step up to a 3/4HP, 10 GPM series pump. That friction loss is determined at 10 GPM flow. When using a CSV the flow will be the same as the amount of water being used. When using a 3 GPM shower the friction loss is non-existent in 600' of 1" pipe. But the 3/4HP will let you turn up the pressure switch from 40/60 to 50/70 if you like, and the CSV will keep the larger pump from cycling to death when using small flow rates.