Internal Overflows
Until September 2000, every toilet cistern had to be fitted with an external water overflow warning pipe. This enabled water to run to the outside of the building in the event of a ball valve failure, thus alerting the owner to the problem.

In the future if a ball valve fails, the water will be allowed to run to waste through the flushing device, into the bowl of the closet, where it will be visible when the toilet seat is raised, thus alerting the owner to the problem.

The internal overflow arrangement is achieved by changes to the siphon flushing mechanism or in the design of the flush valve.

This simplifies the plumbing-in of WC cisterns removing the need to make a hole through the wall of the building for the external warning pipe. 

6 Litre Siphons
The flush volume of the WC is now reduced from 7.5 litres maximum to 6 litres maximum for all new WC suites. 

This change, comes into effect on 1st January 2001.

For a repair and replacement installationswhere the existing WC bowl remains unchanged, a 7.5 litre Cistern can still be fitted, however, all new WC installations must be at 6 litre maximum.

Dual Flush Siphons
The new Water Regulations also allow the installation of dual flush siphons. When dual flush is provided, there must be a very obvious and permanent marking to the suite which makes the user aware of its operation. The maximum ‘full flush’ is 6 litres.

Flush Valves

New Flush Valve  

The use of high quality, modern, tested and approved flush valves as an alternative to the siphon becomes legal for use in the UK from 1st January 2001. Flush valves will allow the installation of toilet cisterns which operate with push buttons rather than levers.

Old Siphon Valve

The flush valve can be of single flush, or dual flush design, however the maximum ‘full flush’ must not exceed 6 litres.

What Do These Changes Mean?
The switch to internal overflow will simplify installation and save time.

The siphon or waste water preventer to give its proper name has been re-developed to work at lower flushing volumes. Other than a slightly smaller mechanism the plumber will notice very little visual change and no change to fitting procedure. Consumers are unlikely to notice any changes.

Installations of the slightly more technically complex flush valve are likely to increase gradually from 1st January 2001.

Consumers will notice the difference between flush valve and siphon operation when presented with the push button technology of the flush valve rather than the lever of the siphon.

As well as helping the environment, these water saving measures can benefit consumers who pay for their water by means of meters.

When Do the Changes Take Effect?
Any cistern operating at 6 litres with internal overflows can be installed in line with the regulations both in the year 2000 and 2001. These will become available during the last few months of 2000.

7 litre flushing cisterns can not be installed beyond the end of 2000, other than for repair or replacement where the existing WC bowl remains in place

Cisterns with flushing valves and mains pressure valves are cleared for installation only from 1st January 2001.