Les, Well wishing (devining) does work and for not only water.
It can be used for finding steel/cast iron pipes. I have seen it done to find a "lost" gas pipe in a field.

Here in Brittany we have Pardons, where there is a morning service 10 or 11am approx at the Fountain (spring) which is dedicated to a saint. There is a fire lit then a parade to the church. At 12noon there is a meal cooked over open fires and served usually in marques in a local field where between 100 and 500 people are catered for. There is often live music throughout the meal and afterwards traditional Breton dancing.
In our village St Eloy is the patron of Blacksmiths. Up until the 1980s farmers would bring there work horses to the Pardon to be blessed.