The HSE investigation focussed on the possibility of a faulty gas distribution system and found the cast iron mains pipe was sunk in sandy-gravelly soil that was classified as "very aggressive" to "moderately corrosive".

BBC: Shrewsbury gas explosion 'no-one's fault' HSE concludes

The rain simulator has 4 in-line spray nozzles, which are feed by a pressurized portable pipe system.

UNESCO: AQUATACAMA