The flip side of this is that Thames Water is clearly not an ongoing concern and can therefore be re-nationalised at zero cost [0]. I believe there's language in the original privatisation deal around this.

Ofc, that doesn't claw back the billions that the PE pirates made off with, but at least the UK wouldn't have to pay them even more to get its water supply under control again.

[0] even if the UK had to pay market value for it, the market value for a business so drowning in debt would be close to zero.