Extracts from the Water Regulations Guide, published by WRAS, which includes the Water Fittings Regulations, Government Guidance to the Regulations and the recommendations of the Water Suppliers for complying with the Regulations.
WATER SUPPLY (WATER FITTINGS) REGULATIONS 1999
SCHEDULE 2
REQUIREMENTS FOR WATER FITTINGS
15.
(1) Every water system shall contain an adequate device or devices for
preventing backflow of fluid from any appliance, fitting or process from
occuring.
where the temperature of the water in the supply pipe or the cistern does
not exceed 25 degrees Celcius.
(3)The device used to prevent backflow shall be appropriate to the highest
applicable fluid category to which the fitting is subject downstream before
the next device.
(4)Backflow prevention shall be provided on any supply pipe or distributing
pipe
(a) where it is necessary to pevent backflow between separately occupied
premises, or
(b) where the water undertaker has given notice for the purposes of this
Schedule that such prevention is needed for the whole or the part of any
premises.
(5) A backflow prevention device is adequate for the purposes of paragraph
(1) if it is in accordance with a specification approved by the regulator
for the purposes of this Schedule.
Bidets with flexible hose and handset fittings and/or water inlets below the spillover level of the appliance, are a fluid Category 5 risk and should not be supplied with water directly from a supply pipe.
Diagram R15.9a
Appliances, taps, combination tap assemblies and mixing valves to which
hoses serving sprays or jets are attached, are a serious backflow risk
and the degree of backflow protection required is determined on the basis
of the fluid category in an appliance or receptacle in which the end of
the spray or jet could be immersed. The zone of backflow risk for any
appliance which is served by a spray or jet atttached to a flexible hose
is the area covered in a vertical and horizontal plane by the spray or
jet with a radius subtended by the length of the hose. This applies to
all types of appliances to which a spray is attached. See Diagram R15.9a
which illustrates the principle involved.
Diagram R15.9b
Bidets, including WCs adapted as bidets, incorporating an ascending spary inlet or utilising a flexible hose or an arrangement with a spray or jet, are a fluid category 5 risk in that the ascending spray inlet could be contaminated with urine or other matter and the spray or jet handset could be deposited in the bidet or WC. Bidets of this type must not be supplied with water from a cold or hot water supply pipe or common distributing pipe. The zone of backflow risk is shown and the highest part of this zone must be not less than 15mm below any cistern serving the bidet.(see Diagram R15.9b)
R 15.12.2
Diagram R15.12.2
A hose union or other tap to which a spray or jet may be attached at the outlet, and which may be located adjacent to ordinary WCs or squatting toilets, is a fluid category 5 risk, in that the tap outlet could be contaminated directly with urine or other matter and, if a hose is provided, the spray or jet could be deposited in the WC. Taps for this purpose must not be supplied with water from a supply pipe, but can be supplied from an independent distributing pipe providing that the highest part of the zone of the backflow risk is not less than 300mm below any cistern serving the tap (see Diagram R15.12.2)