London’s sewers are the ideal environment for rats to live and breed. There is no way to eradicate rats from the sewers. They have happily lived there, from when they were first built by the Victorians in the late 19th century.
The “Wet Wipe Fairy” is a legendary creature that we have never actually met, but as drainage engineers, we know that she almost certainly exists.
This is a question that often comes up when our engineers have been out to unblock a toilet, sink or drain at a rental premises anywhere in London.