The question of whether to hold on until a familiar, clean facility is reached, or to bite the bullet and gain immediate relief, is one which faces everyone at some point.
A possible solution is now being offered to iPod users, who could soon have the power to choose their loos with confidence.
A free interactive guide to public conveniences, appropriately called pPod, offers audio and text information on their whereabouts, opening hours, facilities and cleanliness.
At present pPod users have access to 114 reviews of central London toilets, but its creators, Nykris, say it could be extended to other cities.
Company employees were sent out across the city to record their thoughts on the state of the capital’s loos.