LONDON (Reuters) - Hundreds of British householders can for the first time cook and keep warm with gas that began its long route to their stoves in their bathrooms.

From Tuesday, enough biomethane gas to supply up to 200 homes will be pumped from Didcot sewage works in Oxfordshire into the grid in the first of several human gas recycling projects which could meet 15 percent Britain’s domestic needs by 2020, according to National Grid.

“For the first time ever in the UK, people can cook and heat their homes with gas generated from sewage,” Energy and Climate Change Secretary Chris Huhne said in a statement.

“This is an historic day for the companies involved, for energy from waste technologies, and for progress to increase the amount of renewable energy in the UK.”

In the joint venture between Thames Water, British Gas and Scotia Gas Networks, sewage arrives at the Didcot works from some of Thames Water’s 14 million customers and their solids are then warmed-up in vats in a process called anaerobic digestion, where bacteria break down biodegradable material to make biogas.

The whole process from toilet visit to gas being piped back into people’s homes takes around 20 days.

As the average person produces about 30 kilos of dried-out sludge, in theory Britain’s 62.5 million toilet visitors could generate enough gas to meet the demand of 200,000 homes -- reducing reliance on imported gas.

“The gas that we are transporting from Didcot doesn’t arrive from the North Sea or abroad, but instead comes from the very homes we are delivering the gas to,” John Morea, Chief Executive of Scotia Gas Networks, said in a statement ahead of a barbecue on Tuesday morning where guests will tuck into biogas bacon butties.

“That’s got to be recycling at its very best.”

Britain already produces millions of pounds worth of electricity a year by burning biogas in power plants but its home-made involuntary gas suppliers will not get a discount on their bills for their efforts.