Toilets account for about 30-40% of domestic water use and up to 90% for offices and public conveniences. As from January 2001, all new toilets installed in the UK have to have a maximum flush of 6 litres. Whilst this is a step in the right direction, the projected flush volumes are often less in theory than they are in reality because new water is entering the cistern whilst the flush takes place. This often means that a 6 litre WC has an actual flush volume of 6.5 litres. This can be avoided altogether with the use of a delayed action inlet valve, fitted as standard to the ultra-efficient ES4 WC, which offers additional water savings of at least 25%. Water-efficient toilets such as the ES4 are specifically designed to clear the pan effectively with smaller flush volumes. Not only are they good for the environment, but where water is metered the financial payback can be as little as 2 – 4 years, depending on household size and local water an sewerage charges. Water saving toilets make sense on all fronts.
Most of the low flush toilets currently available on the UK market are dual-flush valves (which use either a button-press or sensor system). These can save water until the valves become faulty when, unless rectified, they leak water continually down through the pan. A study of US WC use estimated that, at any one time, 20% of toilets were leaking. Valve mechanisms are also less robust than the traditional UK siphons, with which UK plumbers are more familiar, and dual flush users may also need to be educated to avoid double flushing. Green Building Store’s ES4 toilet is the answer to this problem – a water-efficient WC with siphon flush which will never leak.
More on the valve vs siphon flush debate
Flush volumes and mechanisms are not the only factors that can affect the water efficiency of toilets. Water can also be wasted while the cistern refills during the flush. It is now possible to get delayed-action inlet valves for siphon flush toilets, which save water by preventing the cistern refilling until the flush is finished.