Marenna,
Naturally occuring water actually does indeed leave clues that any astute observer can pick up on. Sometimes these are only small, even imperceptible to the untrained eye, but they do exist and offer rational explanation for the being able to pick natural water. Then again, many non-dowsers have been just as accurate - there are many examples of these people being able to "locate" underground water pipes...by drawing a line from the water tank to the faucet beside the house.
The thing is, many dowsers do actually claim to be able to perform successfully with pipes and water hidden in glasses and so on. Many also claim to be able to detect oil, various metals, objects, people, etc, under similar conditions. So these are testable claims that they are making.
The basic testing process runs like this:
1. The claimant assures that the test setup is fair for them.
2. They set a success rate they believe they can achieve in this test setup.
3. They assure that their dowsing ability is operational on the day of testing.
4. They assure that the test setup is free from any interference that would throw their dowsing off.
5. They prove to their own satisfaction using dry runs with targets in open view that their dowsing ability is quite operational, and that they understand the test process.
6. The testing is then conducted identical to the dry run, but with blinded targets. The tests are repeated a number of times to give a series of results.
7. Evaluate scores against the claimant's expected success rate.
So it is not like the skeptics are trying to put dowsers in a place where they are uncomfortable and cannot perform in an effort to discredit them. All effort is made to ensure that they have conditions they can perform successfully in, without breaking from adequate testing controls.
So far, no dowsers have ever scored better than chance under fair and equitable conditions such as these. Certainly they have never scored to their own expected success rate.
