Posted: 4/24/2026 2:42:53 PM EDT
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Have some friends with a well issue situation. Friend bought a house in the country. Let’s call it house #1. House #1 was built many years ago and the well is old. It’s only around 250ft deep while most wells in the general area are 4-500ft. 5 or so years ago, the house owner at the time split off another piece of land and her son built a house. Let’s call that house #2. Both houses are on 10 acres. They connected house #2 to the house #1 well so it supplies water to both houses. All seemed good. My friend then bought the house #1 (with the well) and another friend bought house #2. The well was working fine until a year and a half ago when house #2 decided to fill a smaller pool. The water running into the pool over a 2-3 hr period started producing dirty water. So, unsurprisingly, the well is limited in how much water it can produce. They both have been keeping their consumption to normal rates (less than 100 gal per day for house #1 and estimated 300 gal per day for house #2). All has been going fine for several years and the well is handling the demand without issue. House #2 wants to put in an inground pool. Not enormous but around 19k gallons. House #2 realizes they don’t have enough available water to keep the pool topped off in the summer so is planning to drill a well. Once the well is drilled, house #2 will stop getting any water from house #1’s well. House #1’s well is unable to be drilled deeper due to the age (I think the casing size is too small). The wells will be about 400 ft apart. Of course, the new well will be drilled deeper. The new well won’t be used to initially fill the pool but will be used to top it off. What are the odds the new well will substantially affect the old well water level? The new well will be supplying normal household water needs and an occasional topping off of the pool. It’s not going to be a commercial business using 100k gallons per day. @TheWellGuy Thanks! |
"It behooves every man to remember that the work of the critic is of altogether secondary importance, and that, in the end, progress is accomplished by the man who does things."
Theodore Roosevelt
Theodore Roosevelt
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You should suggest that they hire a water service for the initial fill. It’s just stupid to try to fill a 19,000 gallon pool off a residential well. |
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My initial thought is that they would not be pulling water from the same aquifer if they were 150 feet vertically separated. I can see the concern that the deeper well would pump the water out of the higher aquifer. I feel that would be extremely unlikely, especially if they're only pumping a residential amount. The existing well already sounds questionable. I cannot see changing the construction of the new well in any way helping or hurting the first well. I believe the fate of the first well is already determined, just unknown. |
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Originally Posted By FredMan: You should suggest that they hire a water service for the initial fill. It’s just stupid to try to fill a 19,000 gallon pool off a residential well. They are. The new well will be used for household usage and topping off the pool once it’s built and filled. I have a 10000 gallon pool and filled it easily off my well. But my well can produce 45 gpm per the well driller and the well pump is somewhere around 10 gpm. |
"It behooves every man to remember that the work of the critic is of altogether secondary importance, and that, in the end, progress is accomplished by the man who does things."
Theodore Roosevelt
Theodore Roosevelt
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Originally Posted By TheWellGuy: My initial thought is that they would not be pulling water from the same aquifer if they were 150 feet vertically separated. I can see the concern that the deeper well would pump the water out of the higher aquifer. I feel that would be extremely unlikely, especially if they're only pumping a residential amount. The existing well already sounds questionable. I cannot see changing the construction of the new well in any way helping or hurting the first well. I believe the fate of the first well is already determined, just unknown. It was brought up that the new well might drop the level in the old well. My thoughts were that perhaps that could be an issue if the new well was going to supply a commercial building or business. But, it won’t. House #2 currently is estimated to use 2-300 gallons per day. Even topping off the pool daily it should still be 3-500 gallons per day at the most from the new well but no longer pulling off the old well. The old well would go to supplying up to 100 gallons per day. They knew this was an issue when they bought the houses. It’s been working but definitely straining the ability of the old well. The new well should solve everything but the only concern they had was if the new well could somehow drop the available water in the old well and “dry it up”. At what point would you be concerned with a new well causing old wells in the vicinity to stop producing water? I’ve heard of it….no idea how common it is….but as I recall every time I’ve heard of it, it’s a business pulling vast amounts of water and then affecting rural houses near it. Also to clarify, house 1 would remain on the old well and house 2 would be 100% on the new well. Thanks for the information!! |
"It behooves every man to remember that the work of the critic is of altogether secondary importance, and that, in the end, progress is accomplished by the man who does things."
Theodore Roosevelt
Theodore Roosevelt
| Well drawdown interference is a thing. If the cones of depression from two wells intersect, the resulting drawdown between them is greater than either of the two alone. Whether this is an issue for your friends' wells depends on the transmissivity of the aquifer, the withdrawal rates, and the distance between the wells. An aquifer performance test using a monitor well to document the drawdown effects from pumping the existing supply well is the only way to properly estimate the combined drawdown effects of pumping the proposed second well. |
| House #1 residents are prepared to drill a new well if needed but they would prefer not to if at all possible. The well now tests good and the water is clear….as long as thy don’t pull too much too fast. Since the limitations were observed, they have been careful not to run too much water at once. They are doing normal usage just not filling any pools. |
"It behooves every man to remember that the work of the critic is of altogether secondary importance, and that, in the end, progress is accomplished by the man who does things."
Theodore Roosevelt
Theodore Roosevelt
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Originally Posted By dairyfarmer: You could probably put in a Dole valve of the proper flow rate that would restrict output. I had to live with a 5 GPM Dole valve one winter when the screen rusted out on an old well. Interesting idea. We were looking at different flow control methods before house #2 decided to drill a new well. New well solves all the water flow issues but they are just concerned if the new well will create a problem for the old well. |
"It behooves every man to remember that the work of the critic is of altogether secondary importance, and that, in the end, progress is accomplished by the man who does things."
Theodore Roosevelt
Theodore Roosevelt
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@TheWellGuy Just to update this…..the new well is drilled and house #2 is no longer getting water from house #1. No issues at this point. We have had lots of rain so presumably the water table is well supplied. The real test will be during a dry spell in the future. But so far, there are no issues for house #1. House #2 has never had good water pressure. They were feeding house #2 with a 1 1/4 inch pipe but the distance to the house was close to 600 ft. The people in house #2 always complained about low water pressure. When the well driller looked at what was there, he said he was surprised house #2 had any pressure at all. It was poorly designed from the start but it’s now running like it should and both houses are on their own wells. |
"It behooves every man to remember that the work of the critic is of altogether secondary importance, and that, in the end, progress is accomplished by the man who does things."
Theodore Roosevelt
Theodore Roosevelt