In a letter addressed to environment secretary Thérèse Coffey, the Lords criticised the government’s “lack of leadership and deep-rooted complacency” following the committee’s inquiry into water regulator Ofwat.

It also said the government was dismissive of its report and made claims that its recommendations were outside the scope of its inquiry, which was an attempt “to avoid parliamentary scrutiny”.

The report looked at Ofwat’s recent performance, in particularly its monitoring of water firms and overuse of storm overflows, as well as its efforts to secure future water supplies.

It said Ofwat needed to go further to hold water companies to account for environmental pollution as well as ensure that companies invest sufficiently in water infrastructure.

An E&T investigation last year found that self-monitoring efforts by water companies were 100 times less likely to find breaches than Environment Agency testing of private wastewater treatment plants...