A vote by MPs could introduce rules ensuring water company bosses do more to prevent raw sewage being dumped into rivers and the sea.
The government hopes proposals to legally require water firms to make a "progressive reduction" in dumping raw sewage into waterways will allow flagship legislation to finally clear Parliament.
But the government's move has been criticised for not requiring water companies to take action quickly enough, allowing dumping to continue for many years to come.
The Duke of Wellington's amendment to the Environment Bill would place a legal duty on water companies to "take all reasonable steps" to prevent sewage discharges, and was approved by the Lords by 213 votes to 60.
The Bill was sent back to the Commons for further consideration enabling the government to table its alternative concession - described as a U-turn by Labour - following a fierce public backlash.
The new proposal would put a legal duty on firms to "secure a progressive reduction in the adverse impacts of discharges from storm overflows".
MPs initially rejected section 141A of Lords amendment 45 to the government’s environment bill, which would have placed a legal duty on water companies not to discharge waste into rivers and oceans.
Local MPs Peter Aldous, of Waveney, Duncan Baker, of North Norfolk, Jerome Mayhew, of Broadland, Chloe Smith, of Norwich North, and James Wild, of North West Norfolk, were among the 265 Conservative MPs who successfully voted in favour of rejecting section 141A.
After an outcry, most of those MPs released statements defending their decision, arguing that section 141A would have been unfeasible to put into practice in its current form.
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