I want to know about low-flow water wells.

October 15, 2009 2:38 PM

I want to know about low-flow water wells.

We're about to move into a house which we've discovered has a low-flow well. As I understand it, this means that if used without forethought, water demand can exceed supply, and the well temporarily runs dry. Experimentation indicates that running two taps is OK, but if we run the shower and a tap at the same time, water shuts off after 15-25 minutes, and stays that way until the well catches up.

I'd like to hear advice, anecdotes, strategies and stories about living with a well, particularly the low-flow variety. Should we spring for a reservoir tank, which should completely (albeit expensively) mitigate the issue?

Bonus points if you've lived with a sulfur well. The house already has a chlorine based sulfur abatement system, but I'd still like to hear about them.

posted by zamboni to home & garden (10 comments total)

My cousin had a low-flow well and ended up drilling a new well. This is potentially a serious problem. Any municipal water close by?
posted by notned at 3:09 PM on October 15

It depends on how many people in your house and how careful you are about conservation.

We ended up building a cistern and diverting rain water instead of trying to make ours functional.

The levels would drop even lower in the dry summer, so it was worse then. Although, from a kid's perspective, my brothers and I never thought we knew from funny until my mother ran screaming out of the shower fully soaped and shampooed on a Sunday morning getting ready for church.

Soapy and wet she ran down the hill to jump in the lake to rinse off because the water had gone dry. Again.

So it was totally worth that. And 25 years later she still gets steamed about it when we laugh (In our defense, we were all under 10).

But it you are going to do it, you will need to turn the water off while you lather and then back on to rinse. Say goodbye to long uninterrupted showers as you now know them if it is really slow.
posted by Tchad at 3:29 PM on October 15

I only know about relatively deep wells with turbine pumps, but some of the concepts will apply to any well.

You'll get terminology here. You have by observation figured out drawdown and to convert that to gallons you must measure the tap and shower discharge in GPM, then multiply by the 25 minutes.

You will now need to know how long it takes to recover - for the liquid in the well casing to return to its static level.

Once you have drawdown and recovery time you can figure out how much your well produces - again in GPM. If this number is considerably less than your desired maximum usage then you need a reservoir tank.

Friends of mine have wells that produce less than a gallon per minute. The strategy a couple of them use is to put low-flow diaphragm pumps in the well, and pump slowly but continuously into a tank until the tank is full. A turbine pump in the well will pump according to its capacity/pressure curve until it runs dry (bad) or until it is deliberately shut off.

Having a tank is a good thing if your well is the only source of water nearby. My county requires me to have 4000 gallons available such that it flows at 200 gpm, for fire suppression.
posted by jet_silver at 3:29 PM on October 15

I had a well with decent flow but it would become low-flow in the summer months. It was gravity-fed and a little higher up the hill than the house. Once I was at home with a new beau and we were going out to shop for the dinner that evening, flushed the toilet and left before hearing the valve shut off. Long story short, no water for the entire evening/night which meant no toilet, no dishes, no water for coffee/tea etc. If you have kids or other people who you can't depend on to be totally disciplined, I'd really consider the reservoir, or some sort of grey water setup for like lundry and dishes.
posted by jessamyn at 3:42 PM on October 15

My sister and I own a cabin in Vermont and have been dealing with a low-yield well for some time.

Do you currently have any reservoir? We have a cold water tank and a hot water tank. Generally when we arrive at our cabin there's enough water to fill both of those and then a bit more. But the well refills so slowly, that it takes days to return to its static level. Since pressure is generated by the pump in the well, we can't really use the water in our tanks unless there's also water still in the well. If you don't have a tank and the problem is simply that your well can't keep up with your short term demand, a reservoir is probably the best option.

A second option is hydrofracturing the well, the modern equivalent of dynamiting. High pressure water is forced into the well to clear the fractures and improve flow. We had our well hydrofracted for about $2000, which improved flow somewhat, but not enough.

A third option is drilling a new well. Well drilling is charged by the foot, plus some fixed costs. We were recently quoted about ten grand for a 500' well.

Does your pump system have an automatic cut-off? If not, you should get one installed. It keeps your pump from frying its motor if there's too little load.

We always try to keep several gallons of potable and several gallons of non-potable water in reserve. Not enough for a shower, but enough to flush and wash our hands.
posted by justkevin at 4:00 PM on October 15

One place we lived had a low flow well, less than a gallon a minute on the good days. Our well head was about 60 feet below the floor of our house. We had 3500 imperial gallon tank at the well head that the well pump filled. Then our house was serviced by a jet pump with pressure tank that drew off the reservoir tank. Flow was bad enough in the late winter that even that wasn't enough if we had any kind of company. We had a guage that would let us know when we had less than a 1000 gallons and we'd call a water truck to fill the tank with town water. It was way cheaper to call a truck out a couple times a year than it would be to sink another well a few hundred feet.
posted by Mitheral at 4:13 PM on October 15

I once lived in a house in Tuscany located near an olive mill. At harvest time, the pump regularly burned out. The electricity company engineer came round to investigate, and discovered that when the mill was working the voltage of the supply to my house dropped from the nominal 220V to around 100-120V and the pump didn't transport enough water to cool itself down. So make sure your electricity supply is reliable.

Don't know whether this would work for you, but the engineer advised me the company had a contractual obligation to supply 220V ±20%, so they were obliged to add a new transformer station along the (looooong) line to my house, which solved the problem.
posted by aqsakal at 12:43 AM on October 16

Big ass tank or new well.
posted by gjc at 5:22 AM on October 16

Really need more details about your well and pump to provide a more effective answer. You didn't provide information on the yield of the well (typically expressed in gallons per minute, if low yours this will be in the single digits or less), well depth/diameter, static water level, and the depth (if submersible) & rating of the pump (horsepower). As indicated in some of the previous responses, additional storage (via a deeper well, a lower pump, or perhaps an above ground tank) provides a buffer that allows for conservative water use and time for the well to recharge. But you could be having other issues that aren't readily apparent, such as pump or pressure tank/switch problems or maybe your neighbor's wells could be impacting the volume of water available to your well. Hydrofracturing & a new well are possible options, but they're pretty expensive without first getting the well system checked out.

So, I suggest getting a reputable well contractor to take a look (it seems like you're in NY and these folks can probably help you identify ones in your area). They may also be able to give advice tailored to the kind of geology and typical well construction methods in that vicinity.

As for the sulfur smell, that's a common problem and there's plenty of resources such as this one out there that can provide background and suggested treatment options.
posted by pappy at 8:38 AM on October 16

Coupla small edits I should've seen, but good luck with this.
posted by pappy at 8:46 AM on October 16