Much has been said here of the magical nature of water.  Here is a paragraph I recently came across.  Violet Firth, in her book: "Psychic Self Defense" published in 1930 under her pen name of Dion Fortune, reports:
     "There is an old superstition that a witch can be thrown off your trail if you cross running water.  It is my opinion that many of these old folk beliefs have a basis in fact, however overlaid by superstition they may have become.  I once had an experience which supports this opinion.
      I was about to take part in an important piece of occult work to which I knew there would be opposition.  I had rather a trying night and I was conscious of a good deal of psychic tension next day.  I decided therefore to walk to the appointed place across Hyde Park to refresh myself.  When part of the way across, I suddenly felt that the tension relaxed, and I was able to go through the work in hand without interference.  I told my friend of this experience, and she asked where I was when it took place.  We looked up the spot on a map and found that I had just crossed the underground conduit which takes the overflow from the Serpentine.  I did not know of the old superstition concerning running water, neither did I know of the existence of the conduit.  Nevertheless, the sense of relief was sufficiently marked to cause me to mention it when I saw my friend, and to be able to indicate the spot where it had occurred."  

Neat huh?  Makes me want to bury a few water pipes in the lawns surrounding the house.  

Brian