Change to the requirements for WCs and urinals is one
of the more significant differences between the former water
supply byelaws and the new Water Fittings Regulations (England
and Wales) and the Water Byelaws 2000 (Scotland).
The Government has allowed flushing devices not permitted
previously in the UK. It also promotes conservation by encouraging
more efficient use of water for flushing. Altered installation
requirements for WCs and urinals should be welcomed by designers
and installers.
Saving water with smaller flushing volumes for WCs
and urinals
About 30% of the water used in domestic properties is for
flushing WCs. There could be considerable savings by effective
flushing with smaller volumes. So WCs installed after 1st
January 2001 must flush with no more than 6 litres, compared
with the present 7.5 litres.
Also from 1 January 2001, dual volume flushing will again
be permitted, with the smaller flush using up to two-thirds
of the maximum. Manufacturers are busily designing and testing
new dual flush 4/6 litres WCs to meet this requirement. Dual
flush cisterns must have a readily understood means of operating
the different flushes and have clearly and permanently marked
operating instructions on or near the cistern.
Existing WCs lawfully installed under the byelaws will not
be affected by these changes. Where an existing cistern needs
to be replaced without changing the WC pan, the replacement
should be of the same size as the one it replaces. A single
flush cistern should not be replaced with a dual flush one.
Performance approval of WCs
Water fittings and materials must be of an appropriate standard
and quality and be suitable for the circumstances in which
they are used. The premises' owner and occupier share responsibility
with the water fittings installer to see that the plumbing
complies with this. The manufacturer should provide evidence
that a WC suite has been tested and is suitable. One reference
is the Water Fittings and Materials Directory, published by
the Water regulations Advisory Scheme, which lists fittings
and materials that have met the relevant specifications and
are acceptable to water suppliers who enforce these regulations.
The regulations list potential standards for demonstrating
suitability, but the absence of agreed European standards
means at present only the Regulator's Performance Specification
can be used. WC components are tested separately for some
aspects; e.g. the endurance test for inlet valves requires
no leakage after operating 200,000 times, but the complete
assembly also has to be tested. Unsurprisingly, testing of
WCs is not a widely known subject. It includes dye removal
to measure the dilution of 'fluid contents' (i.e. urine),
sawdust removal (to check adequate washing of the bowl) and
the removal of water-filled artificial sausage skins (for
testing the obvious), as well as the measurement of flushing
volumes, water trap seals and other tests.
Introduction of alternative flushing devices
The regulations aimed to be less technically prescriptive
than the byelaws and to allow innovation. Consequently, in
addition to the traditional British syphonic flushing device,
from 1 January 2001 WCs can be flushed by drop valves and
flap valves in cisterns. Except in houses, pressure flushing
valves connected directly to supply or distributing pipes
will also be allowed, provided a minimum flow rate of 1.2
litres per second is available at the appliance.
Urinals can be flushed with a manually- or automatically-operated
cistern or by a pressure flushing valve. Flushing must be
prevented during periods when the building is unoccupied.
Warning pipes and overflows
Traditionally, British WC cisterns were required to have
a warning pipe, usually known as the overflow', which discharged
if the inlet valve leaked. The discharge was usually made
outside the building, although a visible discharge via a tundish
or sight glass into the flush pipe of the WC was permitted.
The Regulations now permit a warning pipe 'or equally effective
device', giving scope for mechanical or electronic warning,
with light or sound etc.
The water supply industry considers that the discharge of
excess water into the pan via the flush pipe, for example
from a bottom-entry, standing warning pipe, can be considered
as an 'equally effective device' and the externally - discharging
warning pipe is not obligatory. This will make installation
easier, especially in buildings where, for aesthetic or engineering
reasons, an external pipe would be impracticable.
Backflow protection
It is essential to prevent the contents of WCs or urinals
from being drawn back into the pipework and contaminating
other outlets. The traditional design of cistern for WCs uses
the simple but effective air gap between the water inlet and
maximum water level in the cistern. Where a solenoid valve
or manually-operated pressure flushing valve connected directly
to a supply or distributing pipe is used to flush a WC, a
pipe interrupter with a permanent atmospheric vent can be
used.This must be installed not less than 300 mm above the
spillover level of the WC pan for safe backflow protection.
The same flushing arrangement for a urinal does not require
a pipe interrupter, as the air gap provided between the water
outlet and the spillover level of the urinal bowl is adequate
protection.
Conclusion
The regulations permit innovation in the flushing arrangements of WCs
and urinals which should be welcomed by users and installers. The regulations
also encourage conservation of water, to the benefit of metered customers
and the environment. |
