how much water is needed in a well?

[Chris142]

My well was drilled in 1964. Originally it was 300 ft deep. Water was found @257 and the pump was set @276.

Worked fine for 3 decades. In 02 we had the pump replaced and they put it @ 297 because the water level was "low". I don't know how low it was.

Had another pump put in last month due to damage to the old pump. The last 9 ft of the well is either caved or just full of dirt which killed the pump.

The water is @270 and this pump is @288 which is 3 ft off the new bottom.

The well guy was concerned about only having 15 ft of water.

He feels that we need to deepen or redrill a new well.

But he wants to go 200ft deeper at a huge expense.

I feel that 60ft would be adequate and 100 would be more than plenty. Especially since I've never had more than 25 ft of water covering the pump. Do I really need a 500 ft deep well?

Thoughts?

 

[earlyre]

how deep are the neighbors?

anyone else in the area have well work done in the last couple years that you could talk to?

 

[Shannow]

I'll give some suggestions based on what I know from drilling ground water monitoring and control stuff.

The ground permeability gives a "recharge" rate, at which the water can get back into the hole that you've left by pumping it out...the only thing that drives the water into the well is the height difference that's created when you pump the water out...recharge rate was tested by pumping the bore dry, then monitoring how quickly it refilled (that was then used to work out the flow rate of groundwater across the site, so different to a well like you have)...

The only immediately available water when you first start pumping is the volume in the well, above the pump, which has to be removed, and provides your initial surge capacity...they probably want more well volume (deeper well, pump under more water) so that a family of ten can all shower at the same time.

Higher head available under those circumstances mean that more will flow into the well, and be available for sustained use...more head available, and more cross sectional area for water to get in.

 

[Chris142]

The water table is weird here. My closest neighbor has water @140.another a little higher than me is @760! 3 doors from him is 650. So there's no rhyme or reason here.

 

[Shannow]

Are the blocks all around the same height (i.e. no-one's at the top of a hill), because that's very very different levels if the ground heights are close...could indicate that the ground is not very permeable maybe.

Try thinking of it like one of those simulated gravity things in the docos...a sheet representing the groundwater and bores dotted around creating localised "low" points.

Given the permeability and direction of flow, and the recharge sources, you can end up with (for example) a ring of bores creating an artificially low "table" for the person in the middle...

 

[eljefino]

Would it be cheaper to leave the well alone but have a large storage tank or cistern in your basement/ at ground level?

It's expensive to move drill rigs around too, so you're paying a bunch just for the guy to show up.

 

[Lapham3]

I learned a bit about this 30+ years ago but with different hydrology than you are working with. In a nutshell, yes it can vary wildly in even closer confines than you are dealing with-some understood, some not. In my state the well drillers are required to relay the well site info to the state adding to a database. Maybe you can get some help/info if the same in Calif-good luck!

 

[Mr Nice]

That's the down side to living in a desert region, you need deep wells.

 

[Al]

I was a well driller's helper 50 years ago and I have always had a well. I think shannow is correct. Your problem is really your pumping rate vs your recharge rate. You have 1.5 gallons per foot so you can see you have only 22 gallons of reserve plus whatever in flow you have while the pump is pumping.

Depending on your use you may be between a rock and a hard place. What is the capacity of the well? Your option short of drilling is to get another tank so you have more reserve especially if there is a problem with capacity.

One word of caution..you may need to use an orifice or throttling valve to control the capacity of the pump or larger storage capacity may work against.

Since you should not need to re-case the well you may need to go deper. Depends how long you are going to be in the house.

Do some research on well drillers in your area.

I notice you are in Cali..I am guessing the water table in your area is going south..that's a major problem in some of the western states. We have out stripped our water supply.

 

[The_Eric]

Has the well ever actually been flow tested?

 

[Donald]

Was any of the pumps they put in higher capacity in GPM?

 

[Donald]

How old is the guy telling you this (to go deeper)? If he is 80 I would believe him.

 

[4wheeldog]

Originally Posted By: Chris142
The water table is weird here. My closest neighbor has water @140.another a little higher than me is @760! 3 doors from him is 650. So there's no rhyme or reason here.


I would think that a valley like you live in would all pretty much be one aquifer. What you are describing sounds more like my area, in the desert, but high in the mountains.

My wife works for a hydrologist. Our geology is such that each well, even just a few hundred feet apart, is going into its own little catch basin. A hollow in the rock catchs water, and you stop when you drill into it. Drilling deeper (Through rock) can empty your well. You might have good water at 300', and your neighbor 500' away may have a dry hole 700' deep.

I do not think that is what you are dealing with in Apple Valley. It probably just has to do with what depths the gravel is at.

 

[Blaze]

My well is low producing. I have a 2000 gal cistern. The key here how you set up your flow rate like filling a cistern in my case. To set my flow rate I have a devise called a "Pump Saver". It has a timer which only allows the pump to switch on every two hours. The pump will then automatically shut off when it senses low pressure. You can set your pump saver according to your wells out put. Your well should probably go deeper and its important to at least have a plastic liner. Some outfits will use well casing to the bottom and then use a machine that punches holes in the well casing to allow water in.

 

[HerrStig]

A lot depends on what lies below. Shale has lots of horizontal seams which conduct water, the deeper the well is drilled the more you open up seams into the well. In other areas the rock is dense and seamless, finding water is a real chore. Wells into sand work but need to be backflushed on a regular basis. Gravel is good, so long as the chunks are big enough to permit good flow around them.
I had a 75 foot well in shale, it went dry one summer even though both my neighbors wells at the same depth did not. Old time well guy gave me a price to go down another 75 and said I wouldn't need more depth than that. At 100 feet he hit 12 agallons a miniute recharge flow (with a smile) which he proved by pumping for about half an hour. He said it would do the whole street, but went the rest of the way anyway and reset my pump at 100. Not had a problem since even in the worst dry spells.
A submersible pump which is too big which can pump down your reserve above the pump. Worse were the old "jet pumps" when any air got into those because the jet was exposed the entire two pipe system had to be bled.

 

[HerrStig]

There are two types of well "drilling machines". One is a drill with a typical drill bit turned by a motor , The other is device which drives a "bit" by impact, like a pile driver, usually called a "pounder". The pounder it is said, does a better job because the impact opens up the little seams from which water flows, while drilling (they say) does not. Drilling is easier and faster. Pounding may be better in rock, but I've never seen a scientific test.

 

[Chris142]

They tested the output in 64 and could not Pump it dry. I'm not having any problems now. The area is very hilly but it seems like the water table does not follow the hills as some houses below me have water at lower levels than I.

The well guy is in his 60's I'd say.the water has dropped 13 ft in 50 yrs.

 

[Chris142]

My well was pounded,not drilled. I have tried pump savers but the y stop working completely which leaves me dry until I bypass them.

Pumps were 1.5 HP, latest is 1 HP low volume. Only 9 gpm but it fills my tank daily.

 

[Blaze]

The problem is your static level and most likely you could continue to kill pumps with the way you are set up. You have filthy water cascading down on your pump. Only 3 ft off the bottom further adds to the problem too if it has collapsed. I would drill at least 60 ft deeper and get it LINED properly and AT LEAST 5 ft off the bottom, hopefully more (personal choice). I would definitely use a pump saver and have it timed to start pumping when your static level reaches it peak level...MUCH EASIER on your pump! This is the proper way to set up a cistern with low producing wells.

 

[Chris142]

I'm not sure what a cistern is.googling one gets me rainwater stuff and we don't get much rain here. I have a steel tank that's 1/2 air and 1/2 water.

Its pressurized by the water level. When its full it shuts off @40 psi.it comes on @ 20psi.

Its worked well since 1964. I am considering a storage tank for emergencies.