On Wednesday, October 24, 2012 11:58:28 AM UTC+1, Gazz wrote:

As others have said, if the water hammer is enough to separate a joint to

the main pipe in the street, then it should have blown the hozelok fittings

off the hose feeding the solenoid as well or before the street joint failed,

The others is wrong.

You can get a huge shock pressure from water hammer. There have been many accidents where water hammer has smashed steel pipe fittings, usually slugs of condensate on starting a steam main from cold.

It's how a hydraulic ram works.