Millions of pounds has gone down the pan through passengers using toilets at London train stations - straight into Network Rail's pockets.
The most loo-crative facilities were at Victoria station, where commuters spent a whopping £834,952 in the 12 months to April 2015; and £2.3m over the last three years.
Second was Euston where nature calls raked in £623,132 in one year; or £1.8m since 2012.
Third was King's Cross where £494,149 or £1.3m was flushed away; and in fourth was Paddington at £425,270 or £1.1m.
The data, released by Network Rail and compiled by getwestlondon's data team, revealed that across Britain's 13 biggest train stations customers have handed over more than £12.8m to use toilets in the last three years - or £4.4m during 2014-15.
This was up slightly on the previous two years where the money-spinning loos raised £4.2m each year.
The majority of the money is retained as profit, for example, in 2013-14, only £1.4m was spent on staffing the toilets and a further £360,566 on items such as soap and toilet paper.
Each visit to the toilet at these major stations costs 30p.
Liverpool Street, Charing Cross and London Bridge also made the top 13 list.
Outside the capital, Manchester Piccadilly topped the list raking in £371,059 during the year; and just over £1.1m over three years.
A Network Rail spokesman said: “Network Rail operates the biggest and busiest stations in Britain.
"Toilet facilities are available at all these stations and are open to everyone, not just rail users.
"The small charge we make for using the public toilet facilities in our stations helps to maintain them, ensures they are fully staffed and prevents misuse such as vandalism and other anti-social behaviour.
"Any profit from station toilets is reinvested in the railway and passenger facilities."
