In message , David WE Roberts
writes
Just had a visit from a very friendly plumber, about replacing an
electric hob with a gas hob.

In passing, he said that he had just had to condemn an installation
where a Polish person had connected the cold mains to the gas part of
the boiler, and the gas to the cold mains feed.
He had told them they would have to call in the gas and water boards
and it would const them £7-8K to sort it all out.

Sounds like ******** to me

There is no such thing as the gas board, and while there would probably
be some purging necessary of the gas main, water pressure is so much
higher than gas pressure that there's little chance of any gas ending up
in the water supply

Just another lying plumber

--
geoff