Recently attended a newly renovated and replumbed property on private water supply (spring, not borehole). Low pressure to house, so 2x storage tanks in loft.
So-called plumber hadn't bothered with lids, hence a nice soup of dead flies and bats feeding both cold and DHW outlets. And the only filter and UV was on just the kitchen tap. So folks had been merrily brushing their teeth with this.
His star turn was to fit a whole house booster pump, but kindly left it to be plastered in within the space between the bathroom and bedroom next door with no visible electrical isolation or access without hacking a hole in a newly plastered wall.
Perversly, there was a bylaw 30 kit filter on the tank overflows.
What a star.