If you are lucky enough to find a source of good potable water then protection it. Use water downstream, and protect the source against all contamination. (Unfortunately, you have little impact on industry, smoke and sprayed chemicals.)

To search for underground water or sources people often use a divining-rod, usually made ​​of metal (copper or steel) or wood, sometimes made ​​of plastic.
The model has two L-shaped rods, bent in a right angle. The short part is about 10 centimeters long and the other 30 to 40 centimeters. Each hand holds a short end with a space between the hands of about 30 to 40 centimeters.
If the rods cross or swing open it indicates what (water, metal, mineral) you were looking for.
The Y - model is a forked twig (often hazel that is hold with the tip or curl forward. The two ends are hold with the thumbs pointing outside. This creates a tension on the fork, and can make it jump up or down.
Sometimes also used is a pendulum, a string with a weight (metal, crystal,...). Often some of ​​the sought good is hung on the end of the divining rod or pendulum.

Dowsing is a tool, the human body itself is the detector. We would have the ability to feel, or to interpret our environment. Things deep in our unconscious mind perceive electricity, magnetism, telluric currents or ‘earth rays’which would be made visible by those tools.

Experiments show that the movement of the witching rod only depends of the diviner’s expectation. Rods are unstable by shape and use, the smallest movement on the ends will therefore also move the point. This ideomotor effect is caused by unconscious muscle movements. The chance that a professional dowser finds water is not bigger than that of whomever, indicating a purely random location. If you think it can help, why not...

A reliable source is someone who guessed right more than once. (Frank. A. Clark)