Ever wondered how the toilets on board planes flying 9000m in the air are emptied?

Take a look at how Air New Zealand ensures the toilets on its planes are up to scratch with a behind the scenes video inside its "pee lab".

The "pee lab" specialists Duan Russell, Jack Westcott and Peter Lowen explain each toilet on board Air New Zealand planes is made up of over 300 parts.

The toilets all have a computer in them and cost US$17,000, the men explain in the first video of a series revealing some of the secrets behind the scenes at Air New Zealand.