And BBC is a conspiracy site:
http://news.bbc.co.uk/2/hi/uk_news/england/manchester/4351490.stm
Idiots who don't think snakes can live in the sewer systems must either have lived extremely sheltered lives or they're just plain stupid.
For comparison there are millions of rats living in every sewer systems around the world. I suggest you remove your toilet in the basement and see what happens. Within a month you're guaranteed to get visitors if you live in a city.