OG, //I trust that this is extremely exceptional. //
It's not. From the link:
//Muslims, Hindus and others in India and other South Asian countries, as well as in the Middle East, use water to clean themselves after going to the toilet.
A jug, called a lota, is filled with water, or a hose is sometimes used. Traditionally, the left hand is used to wash after going to the toilet, while the right hand is used to eat.
In Islam, there are a set of practices laid out regarding toilet etiquette.
Although they are not compulsory, many devout Muslims follow the teachings.
The Qadaa' al-Haajah code states that one should clean their private parts using water and their left hand, or three stones.//
Perhaps local councils should ensure that stones are provided in all toilets.
In a similar vein, efforts being made in some quarters to encourage people to sit on toilets, rather than stand.
http://www.bbc.co.uk/news/uk-wales-south-west-wales-16983788