In simple terms, water flows underground. This flow has a direction, and, usually, the flow is under pressure. This flow causes the water to erode the rock it flows through, peeling off electrons as it does and generating a weak electric current. Acording to physics, there is also a weak magnetic field created by this current flow at a 90 degree angle to the flow. It is this weak magnetic field that causes issues with the body.
According to the farmers I have talked to, cows and sheep will graze over underground water, but will not sleep there. Plants will grow shorter or not all over an underground stream. Babies will play over an underground stream, but will do their bes to move wawy from the stream to sleep. If they can’t get away, they will complain (cry, fuss). As adults, we don’t seem to retain the sensitivity of babies. We can sleep over flowing water. These flowing waters, and the magnetic fields they create, can wreak haoc on our hormones, disrupting sleep, causing hormonal imbalance, altering gut bacteria, and even setting the stage for cancer.
The better options are to arrange your sleping area away from underground water. If that can’t be accomplished, then mitigating the water and its electrical and magnetic fields is the solution.
Source: http://water.usgs.gov/edu/earthgwaquifer.html