Had a similar problem over a month ago, water pump run on without demand, and some of the screws were loose. Not the owner, just the pump. It didn't resolve the problem, but eventually, a few days later and after retightening every line and valve and fitting, it did eventually stop. Never had that happen with a ShurFlo before. Hope it's fixed, it was fine for the rest of the trip.
2018 (2017 Sprinter Cab Chassis) Navion24V + 2016 JKU (sold @ ????)
2016 Sunstar 26HE, V10, 3V, 6 Speed (sold @ 4600 miles)
2002 Roadtrek C190P (sold @ 315,000kms)