1gpm well for irrigation

[Brad Perkins]

I am building a house and had a well drilled but unfortunately ended up with nearly a dry hole... 1 gpm. They went to 180 ft hoping to hit a better vein when I told the guys to stop. So I have around 200 gallons of storage as it sits. They told me I should have enough water for the house but I'm skeptical. Fortunately I have rural water at the road but I have to trench it 1500 ft to the house. Was hoping to drill a good well near the house to avoid the hassle and monthly utility. So now I have a well without a pump that I'd like to use for irrigation instead.

What size pump would I need for this? Do I still need a pressure tank?

My thought was maybe a sprinkler system but I'd be ok for now moving a sprinkler around by hand. My main concern of course is running the well dry and harming the pump. I'd also like to hook up a couple hydrants to water trees. I see a potential disaster there turning on the pump with the hydrant off and burning it up. I think a pressure tank would prevent that problem... But I'd rather not have a pressure tank if there is a way around it. Thoughts?

 

[Valveman]

1 GPM is 1440 gallons per day. You could supply 5 houses with that much water. Or you could supply one house and have 11oo gallons per day to irrigate with. You will just need a storage tank and booster pump to be able to utilize a 1 GPM well. You can still avoid the hassle, expense, and bad taste of chlorinated city water.

Here is a drawing of a storage cistern system and booster pump. You will still need a pressure tank, but with the CSV you only need a 4.5 gallon size pressure tank.

And here is info on a Cycle Sensor to protect your well pump from running dry.

 

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[Reach4]

Initial thoughts... you did not say how deep the static water level was and what depth the water-bearing stratum was.

If you don't do surface storage and want to supply the house and controlled irrigation, I am initially thinking 1/2 hp 5 gpm or 1/2 hp 7 gpm pump with a pressure tank. For irrigation without a cistern, you would like to try to consume the output of the pump during the irrigation.

For filling a cistern, 1/2 hp 10 gpm for the submersible because it would not need to develop pressure. Then a similar submersible could be horizontal in the cistern to provide pressure to the house and sprinkler. A big-enough cistern could also be used for fire fighting.

Either way, a system to automatically shut down the pump for an interval , such as Cycle Sensor, will make things easier with less worry. If you did not do that you should keep an eye on things. A cheap low-pressure-cutoff pressure switch may or may not be sufficient help.

To measure your water depth from up top, you can run a piece of plastic tubing (open at the bottom) along side your wire. A small air compressor teed with a pressure gauge would tell you how deep the water is. It measures how much water there is from the surface of the water to the bottom of the tube. For every 1 psi on the air gauge, you have 2.3 feet of water above the pump.

I am not a pro.

 

[Brad Perkins]

The water is about 40 ft from the surface.

I do not want rural water due to the chemicals they put in it and the expense. I plan on installing a reverse osmosis filter on the fridge to drink. But I'm on it now and the cost is about $45 per month which isn't terrible. Now if I watered with it then things get $$$. That's why I figure I'll just use the well for irrigation purposes. Giving it some more thought, I could put a pressure tank in the back corner of my garage which is the closest to the pump. My garage isn't insulated but I could always drain the tank before winter.

Would a 1/2 hp 5 gpm pump be able to pump the water from.. 160 ft down? How deep do you set the pump on a 180 ft hole?

 

[Reach4]

I do not want rural water due to the chemicals they put in it and the expense. I plan on installing a reverse osmosis filter on the fridge to drink. But I'm on it now and the cost is about $45 per month which isn't terrible.

That is very expensive vs buying, but maybe the convenience is worthwhile to you. I presume it is not a cash flow thing.

Hard water is harder on RO units. With a service swapping out your membrane, the increase frequency of swap may not bother you. I don't know your hardness, nor do I know how to turn that into a prediction of membrane performance and life.

Do know that some RO units are more water-efficient than others. Could be 1:1, or could be 5 or more gallons of water discarded for every gallon of RO water produced. I expect hard water worsens the performance. Some systems pipe the discharge water to the hot water tank.

 

[Valveman]

With the static level at 40', and the pump set at 170', there would be 200 gallons stored in the well. This would be enough for the house. You could also irrigate at 10 GPM for 20 minutes. But then you would have to wait 200 minutes to do it again. A cistern could store water 24/7, so you can irrigate like you want. If the water doesn't test bad, you don't need an RO. They also strip out the good minerals from your water.

 

[Brad Perkins]

With the static level at 40', and the pump set at 170', there would be 200 gallons stored in the well. This would be enough for the house. You could also irrigate at 10 GPM for 20 minutes. But then you would have to wait 200 minutes to do it again. A cistern could store water 24/7, so you can irrigate like you want. If the water doesn't test bad, you don't need an RO. They also strip out the good minerals from your water.

I fear we will run out of water showering in the evenings and doing laundry on the weekend.

 

[Valveman]

You would have to be careful not to let that happen. That is why you need a cistern.

 

[Reach4]

If you build a system with no cistern, you could see what happens. The pump down the well would be suitable for filling the cistern if you converted later.

If you install a cistern for home use, you may need to take steps to inhibit growth. Blocking light might be enough for that. Would the tank be in a basement, where it would be safe from freezing?

https://www.home-water-works.org/indoor-use/clothes-washer

 

[Brad Perkins]

When I hear the word cistern, I start to think rural water would be so much less work. I'd also have to maintain a water softener since the well is likely really hard. Rural water isn't too bad but I can taste the chlorine so we don't drink it. I really want to get away from bottled water which is why I thought the R/O unit would solve that problem.

 

[Valveman]

If set up correctly a cistern is no extra work. Have you done a water test? Your well water is probably better than bottled water. Hard just means it has minerals in it, and most of those are good for you.

 

[Reach4]

When I hear the word cistern, I start to think rural water would be so much less work.

Would the phrase "non-pressurized storage tank" be less scary? https://www.plastic-mart.com/category/109/plastic-storage-tanks

 

[Brad Perkins]

What size tank would be suitable? 200 gallon?

 

[Valveman]

300 gallons is all a house will use in a day. How much will you be irrigating?

 

[Brad Perkins]

With the cistern setup, I'm assuming a float activates a switch that fills the tank from the well. Then the pressure switch on the pressure tank activates the pump in the cistern? How would I then get pressure out to hydrants outside?

 

[Valveman]

You either tee the hydrants off the booster pump, or put another control on the well pump so you can use it directly.

 

[Brad Perkins]

We recently got a digital upgrade to our water meter so I called the rural water district to see if they keep daily logs. The most water we used in a day was 250 gallons. So a 200 gallon well and 300 gallon cistern should easily meet our needs. You guys have been a lot of help!

 

[Reach4]

For your submersible in the tank, you will ideally put a flow inducer sleeve on that. Search. If you don't find posts on that, let us know. It is cheap and simple.

Usually you bring the water out of the top rather than through a bulkhead connection on the side of the tank.

If you were in California, they would want your cistern tank to be thousands of gallons for fire fighting. Your tank would probably be outside, because basements are rare in California.

 

[Valveman]

A submersible in the cistern would also be more quiet.

 

[Brad Perkins]

A 300 gallon tank would easily fit in my mechanical room next to my central air unit. You think a guy with zero experience with the stuff.. If you can't tell... Could install this himself? I'm a decent shade tree mechanic and do home repairs myself. I'm weak on electrical but I have some plumbing experience.

But it sounds like I'll need a line coming in to the pressure tank and a line going back out of my basement for the irrigation.