someone explain how a private well works

I am looking to buy a house in the country - most have private wells for water. I know how a muni. well works (basically the water is pumped up to a tower then gravity fed to the houses) but with a private well I don’t think there is a tower.

Is it just a pump that provides pressure? is there a holding tank in the attic that provides gravity feed? compressed air? what provides the pressure at the faucet?

As a country guy, I can take a stab at answering this: Basically, an electric pump provides pressure. There are no tanks that I know of, unless your well goes dry and you have to buy (and pay to fill) a cistern. Goddamn rainless slowly-desertifing climate. :mad:

Anyway, your pump does the work. So you’re screwed if the power goes dead. I’m thinking of installing a wind farm, actually.

Most private wells have a pump that pumps the water into a closed tank. On the tank is a pressure switch which will turn off the pump when the preset desired pressure in the tank is reached. Since you cannot compress water, there is an air space at top of tank to allow for pressurization. As the water is used from the tank, the preset pressure switch causes the well pump to start again to bring pressure back up.

a cistern is , I assume, a big tank to hold water?

if the electric pump pumps the water into the closed tank - compressing air at the top. It would seem to make sense that as you run the water (esp. flat out like from a hose) the pressure will drop till you get to a point that you are just getting you water from the pump directly. If so how long should this take and how low does the pressure drop to (practiaclly speaking) once this point is reached.

Also how big is this closed tank and where is it usually located?

I’m by no means experienced with the subject, but I’ll add that my stepbrothers have a house with a water well. They have a pump and a tower (~50’) with a tank that I’d estimate at 300 gallon capacity. So I’d suppose that’s an option some people do pursue.

FWIW, they share the well with the neighbors (I guess that might have something to do with wanting a reserve capacity).

thanks barney that’s want i guess **Hail Ants
** meant

What sward said. There’s an air bladder in the tank that forces the water out and maintains the pressure.

An important issue (in our part of the country, anyway) is if the well water is fit to drink, or if you have to run it through a reverse-osmosis system to make it potable.

And hey, Derleth, we’re practically neighbors (well, I live about 400 miles south of you, but you know …). This drought is none too cool, huh?

At my parent’s house the tank IIRC, was smaller in size than my current 60 gallon water heater. Pressure was low enough where flushing any toilet led to a very noticable drop in pressure at any other running tap in the house. Of course, the tank was also in the basement, which probably isn’t the most efficient location.

When buying a house with a private well, make sure you get a water quality test, and flush the toilet while running the shower.


Before you buy a house on a well, it is a good idea to have it tested. Your mortgage company may even require it. You typically need to test that the water is safe to drink, and that the well has a sufficient capacity to meet your needs.

One important factor is the continuous production rate of the well. A well will have a certain amount of “storage” in the ground, as the pump is sitting below the water table in the ground. When the pump runs, water flows to the pump from the adjacent rocks and the water level around the pump goes down. You can visualize the water table forming a cone around the pump as water is drawn from the center and trickles in from the adjacent rock.

If the water flows in from the adjacent rocks faster than you use it up above, there is no problem. If you pull water from the well faster than the well’s recharge rate, you will eventually hit the point where there is no more water to pump, and the pump shuts off for a while to protect itself. A water pump will burn up if it tries to pump air.

When you test the capacity you first have to drain down the in-ground reserve, that is until the pump shuts off the first time. Then you see how much water the well can produce over a 24 hour period. That will give you the recharge rate. The recharge rate changes over time as varying amounts of water reach the water table, but it gives you a baseline. Lots of household wells in eastern states are having problems for the first time as the drought lowers the water table and reduces the flow into wells.

If your well does not produce enough water there are some options, including cisterns for more capacity for high-use times, fracturing the well to increase the recharge rate, or drilling a new well.

There may be regulations in your neck of the woods that dictate the distance a well must be from a septic drainfield; if you’re in the country and looking at well water, I assume that you don’t have access to sanitary sewer.

New York state is a tough environment for wells. If you’re anywhere near Buffalo or Rochester, you’ll be right above bedrock, and there’s no aquefers to speak of. I’ve got friends in Wyoming County, and their well sucks air more often than not.

My advice: move to Buffalo, and enjoy the luxury of the cheapest real estate in the United States, along with UNMETERED MUNICIPAL WATER.

I’m pretty lucky in this way, actually: My water is pure enough I can drink it without much filtering. Most water in my region is very alkali and is unfit for humans. All of my close neighbors have cisterns, which are, in fact, huge underground tanks that hold drinking water. Having a large truck to haul massive amounts of water around to fill the cistern is a big plus. :slight_smile:

No freaking lie. We’ve gotten some snow recently (yeah, snow in mid-April) so we aren’t in dire straits as far as water goes, but I think we’re still technically in drought conditions. My well went dry a few months back, which is how I know so much about cisterns. The water came back in a week or so, but that was not a good experience.

Seeing a ‘fog’ of dust that makes the landscape look like a cheap FPS is not freaking good. Neither is seeing ‘thunderheads’ made entirely of your own region’s dirt. :mad:

In our house, located in south Jersey, the well water has been
tested unfit to drink, so we had a line of municipal water put in for
consumption, leaving the well water for outside spigots, hoses,
and sprinklers.

Another things to consider on wells is the hardness of the water. Even if you like the taste of hard water, you need to consider how much mineral content is flowing into your water system. I had a water heater reduced to about 1/3 capacity because the previous owners both removed the filtering and failed to flush the hot water tank. The bottom of the tank filled up with calcium and actually destroyed the lower heating element.

I do not have an informed opinion choosing between filtration or water softeners, but you need to be sure you have one of them if your water has any serious mineral content. (And if you go with filtration but skimp on changing the filters, be sure to flush out your water heater a few times a year.)

Pumps come in two varieties: 1) above-ground pumps that any ten-thumbed, mechanically challenged shlub can replace (Speaking!); 2) in-ground or submersible pumps that are placed on the end of the well’s service pipe and pushed or dropped (gently) to the bottom of the well and generally need some expertise to install.

The above-ground pumps only work to a certain depth, below which submersibles are required. The above-ground pumps are a lot cheaper–and they last a lot longer, but if your well is too deep (or you really need the higher pressure), then you need to go with the submersibles. (Submersibles also require (I believe) a 4 inch pipe, while above-ground units can get away with 2 inch (or even 1 inch) services.)

If you are buying and not building, ask when the pump was last serviced. The above-ground pumps can go 20 years or more with no service at all, I have never heard of a submersible lasting eight years. (They may last 40, but I have never encountered one that got to 10.)

Look at the pressure tank. If it has a little clam-shaped device on the outside with a separate thin water line going back to the pump, it is ancient. The clam-shaped device has a diaphragm inside that is used to let the pump know when the tank is filled. Periodically, the diaphragm tears (wears out) and needs to be replaced. Replacing it is merely a matter of undoing some screws and getting a bit wet, but finding the blasted part can be a real adventure. (The box my last repair kit came in says OLEN MANUFACTURING CO. 141 ONTARIO ST, FRANKFORT ILLINOIS, RAC-33-3A Repair Kit but I can’t find the part number or the company name on the internet.)

Many houses have been built over the wells. (It makes servicing the plumbing in mid-winter much easier.) However, it is difficult to drive a well-drilling rig into the basement, so replacement wells are pretty much always outside with a pipe running through the wall into the basement. Many wells last virtually forever, but in some soil types the input clogs with grit and a new well must be drilled. This is really hit-or-miss, however. I have a neighbor about 400 feet from me who has had three wells drilled in 15 years. No one else on either street in the subdivision has had a single well replacement of which I am aware.

If some of this sounds scary, it certainly can be. However, my Mom has been in her (47 year old) house for 34 years with only one well and pump replacement and I have been in my (44 year old) house for 16 years and have only had to replace the pump and pressure tank two years ago.

This thread is so interesting. We in Australia use rain water tanks and get our other water from what you call a well to what we call a bore. we use two types of pumps, desiel and electric. these are mainly found on farms who use that water for irrigation. Most towns have ‘twon water’ water that is pumped to homes from a damm or water resiviour that can be up to 300kklm from the town or city.

The differences are amazing between the two countries

Also you might want to test for radon. My cousin’s husband had cancer a while back, they have a well, he’s fine now but they really have taken all possible measures to ensure that everything is prefectly clean re: their water supply. They have a very expensive reverse-osmosis, ultraviolet, etc. system that removes absolutely everything from the water. In fact they’re not supposed to store tap water in a plastic container because the water is so “empty” of everything that it picks up the plastic. (Layperson’s terminology!)

My grandparents had a spring that fed into a tank. Water was gravity fed to the house. Grandpa put a pipe under the dirt road and used creek water (pumped with a gasoline engine) to water his field.

I recently installed a new shower fixture. One of the “features” that it came with as a pressure balancing property that kept the hot and cold mixture ratio the same should it lose pressure in one of the two lines.

It’s nice, there’s no more “Flush! ARGH!”.

I believe it’s code for new construction in some places now.

BTW, I also grew up with a well. We had pressure tank in the basement that was filled via an electric submersible pump from the outside well. The well was originally something like 200 feet deep but was later redrilled to 405 feet because we got tired of running out of water each summer.

A submersible pump is going to be required for anything over 32 feet deep. That’s the maximum depth from which you can pull water. After that, you have to push the water up, requiring a submersible pump.


Lifetime of submersible pumps:
Fortunately mine has lasted at least since 1984 when I bought the house and, probably, since it was built in 1980. This in spite of the facts that the house is cheaply constructed, the water has large abrasive chunks of mica in it, and my pressure switch malfunctioned a couple years ago causing the house pressure to soar over 120 psi (the limit of the gage scale) for a couple weeks before I figured out what the problem was. Since the well is 220 feet deep the pressure at the pump must have been over 230 psi. I live in mild daily fear that my luck is about to give up, but so far so good.

Depth of wells with pump at the top:
I grew up in a house with the pump at the top. It didn’t pull water up - there was a recirculating loop between the top and bottom of the well, with an eductor (sp?) at the bottom. This is a fitting that uses a venturi to drag additional fluid into a fast jet; they also found use on steam locomotives to push more water into the boiler. So somewhat more water comes up the return side of the loop than the pump pushes down in the first place. I think there is no specific limit to how deep these can work.

Shower versus flush:
If using another faucet causes the shower to weaken, the fault is the narrow or clogged pipes in the house. The pressure in the tank is staying about the same as you open and close different outlets.

My calculations give 33 feet. Ah, well, close enough. :slight_smile:

(Hijack: today’s puzzle-where does this number come from? Hydraulic engineers and physicists are disqualified from this game. :smiley: )

Thanks for the info. btw the 32 or 33 ft depends on basically air pressure and is correct at sea level. Higher elevations will lead to lower distance.