As a Yank, I'm sure I don't understand how British water is handled. In the US, water provision is private also. However, the profits are limited and universal service within its area is a requirement. This makes utilities (water+power) a reliable investment if not great.

[This is not to say there are no issues; some companies get bloated or incompetent to the point of hilarity. Sometimes they leave increasingly-serious problems for decades out of apathy or laziness. Or the costs of fixing old infrastructure can grow out of the reach of the firms.]

However, we know that private electricity companies caused fires in California via wire is that they had already collected an approved rate increase to correct -- but then paid the money out to shareholders instead.