iPhone application Toilet Rush puts the city's public lavatories on the map

Leo To always made it to the men's room, but admits he had some close calls. The creator of Toilet Rush is explaining what inspired the app that informs users about their nearest public lavatory, and its condition and amenities.

"I often couldn't find a toilet," says the 31-year-old tech entrepreneur. "I'd have to queue at a restaurant for a drink, hopping with desperation."

With Toilet Rush, those days are gone. The Chinese-language app, which has been downloaded more than 100,000 times and been No 3 in the Hong Kong Apple app store, uses GPS data to help users search for toilets within radiuses of 150 metres and upwards.

While the app began with just 200 toilets, entered by To and his team, there are now listed 4,000 places to pee, thanks to user-generated content.

The secret, he says, is its ease. The app is free to download, works on Android and iPhone, and does not require users to sign in - "When you need to go there isn't time for that."

Consequently, it's simple for those who find a new loo to rate and locate the facilities while they are in the cubicle.

Icons next to the plotted toilet indicate whether there is toilet roll, drinking water and the average waiting time. There is also a comments section.