I'm not sure if this is the right section to post this, but the water in the well, at my grandmothers places is disappearing somewhere. Description of the problem: The chances of it being the well itself is, I'd like to say, almost impossible. The main problem is that the water doesn't start disappear when you open the valve at the well, but often takes days before it starts to disappear. The water level in the well even rises before it starts to disappear. Description of the plumbing: There are 2 one family houses located inside a valley. The well is located on the wall of the valley. The well itself is made from 2 concrete rings each with a height and diameter of ~1m. The well feeds from one of the underground springs that litter the sides of the valley. From the well there is ~100m of pipe, that runs to the base of the valley. At this point the pipe splits and goes to each of the 2 houses. Also at this point there is a tap on the line going to the neighbors house. From this point there are another ~30m of pipe to each house. Also note that no pumps are used, it works on the height difference between the well and houses. All of this, I guess, was built at least 50 years ago, which means that there aren't many people who knew anything much about it. As it turns out most of the system used metal pipes, only the part from the neighbors house to the splitting point and another ~10m toward the well had been replaced 15 or so years ago, when there had been a leak. First repair attempt: We started working on the well itself first. After all this time the movement of the valley side had dislocated the upper concrete ring, so we pushed it back. We also replaced the the metal pipe going into the well with a proper PVC pipe. Added a valve so the well can be closed without having to stuff things into the pipe. Found 2 holes in the 2m of metal pipe that we dug open to do this repair work. Sadly this didn't solve anything. Second repair attempt: Since the water pressure coming from the taps in the houses was still rather high, even when the well was empty, we decided to replace all the metal pipe from the well to the point of the old repairs. Originally we wanted to remove the old metal pipe, but gave up on that since the whole side of the valley was made up of wither rough gravel or clay. So we dug a new trench and placed a 42mm PVC pipe. The only real issue is that we had to place it, connect it and closes the trench so that the excavator could get down again, so we couldn't really check the pipe. The odd things was, we connected everything on Sunday, Monday we came back to close the holes at the places where the connections are. At this point the well was still full of water. The next 3 days were rainy so we didn't go to grandmothers place. Comes Friday the well is empty. Third repair attempt: So now we decided to dig open the point where the pipe splits and goes to each house to see how everything looks there. Didn't find anything there, but we confirmed that the pipe going to grandmothers house is made from metal. On Saturday we dismantled the connections and connected only the neighbors house. Until Wednesday we were working to replace the metal pipe going to my grandmothers place with a PVC pipe. All this time the well was full of water to the point that it flowed out from the overflow pipe of the well. On Wednesday we remade the point where the pipe splits and goes to the houses, so that we now have a valve for each house. After that we connected our house. At this point we had drained the pipes so we could work on the connections at the split point. So once we opened the well it all flowed into the empty pipes. Thursday the well had mostly recovered the normal level, it wasn't flowing out from the overflow pipe, but I attributed that to more usage and the fact that we are probably losing some water at the point where the concrete rings connect. We couldn't go Friday, so now it's Saturday. I went to check the well right as we got there, still no water flowing from the overflow pipe, but the well was still almost full, even 1-2cm more then Thursday. Fast forward 6 hours, the water level has dropped by 7 cm. Fast forward another 5 hours the well is empty. At this point we decided to closes the valve inside our house and see what happens. After ~12 hours the well was still empty. End At this point I just don't know what to do anymore. Given the fact that the water in the well was holding while only the neighbors house was connected I want to assume that all of the pipes there are ok, but that means that the only remaining pipes that could leak are the 2-3 meters of metal pipe under the kitchen in grandmothers house. The soil under the house is sand, but I'm still doubtful if hundreds of liters of water can drain down in such a short amount of time without anything coming up. Sorry for the huge wall of text. I'll try to answer any other questions about the system as best I can. Does anyone have any idea what could be wrong or any idea how to proceed about finding anything out? I'm thankful for any help that can be provided.