This is because of the Sewers in Rivers
[The House of Lords has blocked
the UK government's
plan to relax restrictions on water pollution
to encourage housebuilding in England.
Lords defeated the government in a vote on
removing the EU-era "nutrient neutrality"
rules on Wednesday evening.
Ministers believe up to 100,000 new homes
could be built by 2030 if water pollution
regulations are loosened.]
https://www.bbc.co.uk/news/uk-politics-66804160