Bidets are specially shaped, low level, wash basins designed for cleansing the lower parts of the body. Virtually unknown in the United Kingdom prior to World War II they are gradually gaining acceptance in this country. It may well be that the well-appointed bathroom of the future will contain a shower cubicle, a wash basin and a bidet rather than, as at present, a wash basin and sit down bath.
There are two, quite different, designs of bidet. The differences between them result in differences in means of installation that should be clearly understood by both the plumber and the householder. In an identical situation the cost of installing one pattern of bidet is likely to be considerably greater than that of installing the other.
The simpler pattern, which is cheaper both to purchase and to install, is usually described as an ‘over rim supply’ bidet. Apart from its shape it is identical to a bathroom wash basin. Holes are provided for pillar taps or, more probably, a pillar mixer. There may be a pop-up waste or an ordinary chain secured waste plug. The bidet is filled with warm water before use in the same way as a wash basin. Bidets of this kind can be plumbed into existing bathroom hot and cold water supplies without any special precautions being taken. If there are 22mm hot and cold distribution pipes supplying %in bath hot and cold taps, reducing tee junctions 22mm to 15mm may be inserted into these distributing pipes and taken to the bidet taps or mixer.
The other type of bidet is described as ‘rim supply with ascending douche’. This has a rim not unlike the flushing rim of a w.c. pan and a douche directing a spray of warm water to those parts of the body to be cleansed. Warm water flows into the bidet via the flushing rim which it thereby warms and makes comfortable for use. When required the water flow can be diverted to the ascending douche.
It is the ascending douche, with its outlet below normal water level, that complicates plumbing installation. With any water inlet of this kind precautions have to be taken to ensure that other water supplies, especially mains water supplies, cannot be contaminated by accidental back-siphonage. The purpose for which the bidet is used makes this particularly important in this case.
To avoid this danger the hot and cold supplies to a ‘rim supply with ascending douche’ bidet must not be taken as branch supplies from pipes supplying any other draw-off point. They must be taken, as separate distribution pipes, direct from the hot water storage cylinder and the cold water storage cistern. As a further precaution the base of the cold water storage cistern should be at least 2745mm above the level of the bidet inlet.
Where there is a two-pipe drainage system a distinction is made between ‘soil’ and ‘waste’ fittings. ‘Soil appliances’ such as w.c.s are connected directly to the drain or soil pipe. ‘Waste appliances’-baths, sinks and basins-are disconnected from the drain by means of a gully.
Plumbers sometimes argue that, because of the nature of the use of bidet, it should be regarded as a ‘soil appliance’ and connected direct to the drain. This is incorrect. A bidet is a wasteorablutionary appHanceand, where a two-pipe drainage system is installed, it should be disconnected from the drain in the same way as other waste and ablutionary fittings.