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31 Aug 2023

Direct Flush – a Technological Revolution

Delabie UK LTD Stand: 521
Direct Flush – a Technological Revolution
TEMPOFLUX 3 recessed valve withstands intensive use

Direct Flush systems offer a sustainable alternative to cistern flush toilets.They connect directly to the water supply and harness the system pressure to flush the WC. Designed to meet environmental standards, DELABIE's direct flush mechanisms are ideal for ecological and/or children’s WC pans. Installing direct flush technology delivers long term dividends in terms of sustainability, improved hygiene and low maintenance.

Cistern flush toilets are common in public washrooms, but are they fit for purpose? Typically designed for domestic use, they are installed through habit and because the initial investment appears low. However, they are typically made from plastic components which cannot withstand intensive use and vandalism. Carole Armstrong from DELABIE looks at how direct flush technology can provide a reliable, efficient and hygienic solution for non-domestic washrooms.


Concerns about cisterns

Cistern-flush mechanisms rely on stored water in the cistern to clear the WC pan. However, anyone who has ever lifted a cistern lid will know that scale and biofilm (a film that lines the insides of pipes) build up over time, affecting the seals and causing leaks which often go undetected. The water seeps silently past the mechanism seal and into the bowl. Thames Water estimate that one leaking toilet can waste up to 400 litres per day. Even if leaks are detected rapidly, maintaining large numbers of toilets is costly and time consuming. Mechanisms can be difficult to access, especially when installed behind IPS panels, and parts wear out quickly with intensive use, needing more regular servicing.


The alternative

Direct flush mechanisms offer an alternative solution. They connect directly to the water supply and harness the system pressure to flush the WC; there is no need for a cistern. The flush mechanism has an integrated stopcock so the cartridge can be removed, serviced and/or replaced without shutting off the water supply. Since these mechanisms are designed for intensive use, they last longer than domestic ones. Although they are more expensive, they are more cost effective thanks to lower maintenance and longer lifespans.


Efficient flushing

Public toilet usage patterns are very different to domestic use, for example schools and theatres see periods of very intensive use during breaks and intervals. One problem for gravity-fed cisterns is the lack of dynamic pressure to ensure a hygienic rinse. If the pan is not cleared in a single flush, the user attempts a second flush, but cistern refill times can be up to 60 seconds. When the full flush volume is not available instantly (due to a leaking cistern or slow refill time) the result may be either user negligence and poor hygiene, or frustration and potential damage (voluntary or involuntary). Direct flush systems are more efficient. The flush uses the system’s dynamic pressure and there is no refill time. Successive flushes are possible, eliminating the problem of flushing with a half-full cistern, and improving hygiene.


Improved hygiene

WC cisterns are a hygiene risk, especially if unused for long periods (school holidays, sports grounds between matches, etc). Standing water, scale deposits and water at room temperature provide ideal conditions for bacteria such as Legionella to develop. These are released in an aerosol whenever the toilet flushes. Direct flush technology eliminates any standing water, and electronic flush mechanisms provide a duty flush to prevent bacterial build-up.


Water savings

Water Supply Regulations require the pan content to be cleared effectively with a single flush of water to maintain hygiene and prevent waste. As mentioned above, direct flush mechanisms provide an effective single flush and avoid additional flushes. Designed to meet environmental standards, most non-domestic direct flush mechanisms offer a 3 or 6 litre flush. These can be adjusted to 2 or 4 litres to suit ecological or children’s WC pans. This also prevents unhygienic splashing and removes the risk of slipping on wet floors.

Some electronic direct flush valves have intelligent flushing systems which identify the duration of use and flush accordingly. They can also feature an ecological setting with a reduced flush length which equates to a lower flush volume to prevent waste.



Public washrooms frequently experience high levels of misuse and vandalism. Heavy-handed users can easily break fragile mechanisms or cause deliberate flooding with conventional cistern-flush WCs. Direct flush valves have vandal-resistant features that prevent abuse. As well as hard-wearing mechanisms, some have an anti-blocking mechanism which flushes once the push-button is released. Similarly, electronic models are activated via user presence, and only flush when the user leaves. The mechanism cannot be activated inadvertently or blocked to flush continuously. For enhanced security, cross wall models are also available for installation in service ducts where users cannot access the mechanism.

Direct Flush systems offer a sustainable alternative to cistern flush toilets. Specifically designed to withstand intensive use, they help to manage water consumption, improve hygiene and are easy to maintain. Replacing domestic style cisterns with direct flush technology will deliver long term dividends in terms of sustainability, improved hygiene and low maintenance.




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