Interestingly this all started in 2017 when a PhD student started aggressively pursuing water companies to find out which ones used dowsing: https://www.theguardian.com/business/2017/nov/21/uk-water-fi...
It seems she did not follow up on the claims of accuracy, or investigate the validity of the practice at all. It was simply immediately discredited as witchcraft and called a waste of public money. I guess this is the scientist vs engineer dilemma at work. The fact that 10 of the 17 water companies were using dowsing 5 years ago before a public shaming shows that the practice could have practical use.