Beginners draining

[Hayman]

which is a remedy you certainly shouldn't entertain when there is a risk of methane

Concerning risks from methane build up, every 'drainer' should read up on the Abbeystead explosion. In 1984 an explosion in an underground water pump house killed 16 people. Because of a long dry period, water had not flowed regularly, and the air space in the conduit was contaminated with methane. Not only can it cause suffocation, but a spark can cause an explosion.