Dowsing has a host of practical applications. One profession which has often embraced it is that of Civil Engineering. Presumably Civil Engineers are practical people and if any method is found to get the necessary results in an efficient manner, then they will adopt it. This was particularly so in the age before reliable underground surveying instruments became widely available.

Here is one application from the 1940s. In which the Engineer used dowsing to successfully locate the position of a leak in a reservoir, a finding later verified by visual inspection.

“Water divining and its relation to civil engineering”, by I. Hopkins.

http://www.dowsing-research.net/blog_extracts/BSD_No28_1940_p128.pdf

Being an Engineer, he puts forward some ideas, current at the tie, as to the mechanism behind dowsing. But also concludes that there was a definite role for the subconscious mind.