KKR & Co. withdrew its bid to invest £4 billion ($5.4 billion) in Thames Water when the US infrastructure giant realized there was little upside to a deal, according to people familiar with the deliberations.

The water company said the decision not to proceed with the equity raise created uncertainty around its plan to stay afloat, raising the prospect of nationalization.

Thames Water customers face the prospect of a £230 jump in their annual bills to help secure its future, after a potential rescue deal collapsed.