A British astronaut heading for the International Space Station has revealed that much of his time will be spent carrying out maintenance in the on-board bathroom.

Speaking ahead of his six-month mission, Tim Peake, 42, explained how making sure the WC system remains intact will take up a large chunk of the mission.

There are currently two toilets aboard the station - in both the Russian and American segments - but both are nearly 15 years old and have a tendency to break.

Speaking ahead of his six-month mission on board the International Space Station, Tim Peake (pictured), 42, has revealed how making sure the WC system remains intact will take up a large chunk of his mission

Major Peake discussed the problem as he was questioned by children from a London primary school in a live link to Nasa's Johnson Space Centre in Houston, Texas.

One of the children, named Eddie, asked the question children want the answer to more than any other when it comes to human space flight - 'how do you go to the toilet?'

Major Peake, from Salisbury, Wiltshire replied: 'The most training we have is not how to use it but how to fix it. It's been up there for 15 years now.

'There's one in the Russian segment and one in the American segment. Thankfully they're pretty identical so they share common parts, but they do break quite a lot.

There are currently two toilets aboard the station (one pictured) but both are nearly 15 years old and have a tendency to break. Major Peake discussed the problem as he was questioned by children from a London primary school in a live link to Nasa's Johnson Space Centre in Houston, Texas

Major Peake will embark for a six-month stay on the space station on 15 December and will perform more than 30 experiments for the European Space Agency (Esa). He is the first British citizen to be selected for astronaut training by the space agency

'So it might not seem like a very glamorous task for an astronaut but we do spend an awful lot of time fixing the loo. In terms of using it, it's really very straightforward.

'It just uses air suction and a big fan to keep everything going in the right direction.'

He added: 'I'm sure there's going to be a bit of a rush to the loo after six hours in the Soyuz spacecraft when we dock and get on board the space station.'

HOW TO USE THE TOILET IN SPACE On Earth, we are used to toilet seats around 12 to 28 inches (30 to 45cm) in diameter, but in space astronauts must contend with an opening that’s about four inches (ten centimetres) wide. They use restraints to hold themselves to the seat, which ensures that no waste can escape while they sit down, and to train astronauts to do this, Nasa has a toilet with a camera inside so they can practice positioning themselves correctly when they sit down. The toilet itself works like a vacuum cleaner, using differential air pressure to suck the solid waste away. The waste is not jettisoned into space, however, and is instead stored on the station to be disposed of on a capsule returning to Earth. The toilet itself (pictured) works like a vacuum cleaner, using differential air pressure to suck the solid waste away. The waste is not jettisoned into space, however, and is instead stored on the station to be disposed of on a capsule returning to Earth Urinating uses a different contraption. Personal urinal funnels are supplied to each astronaut, which attach to a hose adapter. When an astronaut uses the funnel, fans suck the urine out into a waste water tank. Toilets on the ISS can cost upwards of £11 million ($19 million), while the entire set-up costs about £150 million ($250 million) This is because the urine facilities are fairly complex; in 2008 astronauts began using a new system than can purify and distill urine into water. This can then be recycled and used for drinking and bathing. To separate contaminants in the urine from the water, the ISS has a spinning keg-sized distiller that creates artificial gravity while boiling the liquid. Eventually Nasa also hopes to generate electricity using the urine in a process known as forward osmosis. Advertisement

Major Peake will embark for a six-month stay on the space station on 15 December and will perform more than 30 experiments for the European Space Agency (Esa).

The children who spoke to him from Queen's Park Primary School in Westminster, London, belong to one of a number of school groups engaged in activities related to the mission.

The aim is to promote an interest in science and technology with experiments involving food, coding, plant growth and fitness.

Mr Peake (pictured), a former Army helicopter pilot, was selected for astronaut training by Esa in 2009. Over the past six years, the 42-year-old has lived in an underground cave, spent 12 days on the bottom of the sea, and has taken lessons in science and Russian. He is pictured in a 'zero-gravity' simulator

Major Peake, pictured in 2012, uses a device that simulates the motion experienced in zero gravity

Mr Peake, a former Army helicopter pilot, was the first British citizen to be selected for astronaut training by Esa in 2009.

MAJOR PEAKE: JOURNEY TO SPACE 2008 Applied to the European Space Agency. Start of rigorous, year-long screening process 2009 Selected to join the European Space Agency Astronaut Corps Appointed an ambassador for UK science and space-based careers 2010 Completed 14 months of astronaut basic training 2011 Tim and five other astronauts joined a team living in caves in Sardinia for a week. 2012 Spent 12 days living in a permanent underwater base in Florida Completed training and certification for space walks 2013 Tim assigned a six-month mission to the International Space Station 2015 Tim will embark on the Principia mission, a long-duration flight to the ISS Advertisement

Over the past six years, the 42-year-old has lived in an underground cave, spent 12 days on the bottom of the sea, and taken lessons in science and Russian.

It is not the first time a Briton has flown in space, but other British astronauts have had private funding - such as Helen Sharman, the first Briton in space in 1991 – or taken dual citizenship.

Major Peake was selected from more than 8,000 applicants and, speaking to MailOnline from the European Astronaut Centre in Cologne, Germany, he admitted that while he had a lifelong interest in space, there had been no clear way into the career.

'As a child growing up I followed the space programme and it was very inspiring but at that point there were no British astronauts so it was not as if there was a set path to follow,' he explained.

After sending in his application, the 42-year-old was invited to take part in the ESA's extensive screening process, starting with a day of tests in front of computer screens.

'It was test , after test , after test , with very few breaks. We did concentration tests and non-trainable tests for one day in Hamburg,' he continued

'Then they tested soft skills communication skills like leadership and followership.'

His forthcoming mission has been called Principia, after Sir Isaac Newton's historic text Naturalis Principia Mathematica, describing the principal laws of motion and gravity.