Delabie marketing manager Carole Armstrong examines how cistern-flush toilets can increase the risk of bacterial contamination in public washrooms and how direct flush technology provides a hygienic and sustainable alternative for care facilities
In the fight against bacteria and germs, the toilet is an obvious source of harmful pathogens. In care facilities this intensifies if the toilet is also used to dispose of vomit and faecal deposits when a resident becomes unwell.
Received wisdom says that when we flush the toilet harmful pathogens are flushed away and regular cleaning will remove any germs and bacteria from contaminated surfaces. However, in 2015, an American study reinforced the hypothesis that flush toilets play a role in the airborne transmission of infectious disease by producing microbecontaminated bioaerosols when flushed.¹
Following a contamination episode, a French hospital found that the epidemiological source of infection was the toilet cistern. Cisterns increase the contamination risk because water is stored at ambient temperatures in ideal conditions for biofilm development.
This, in turn, provides a safe haven for bacteria to develop. These bacteria are released in an aerosol plume during flushing, but they can also spread back through the pipes and colonise the system.
Flushing is essential for effective hygiene, so airborne pathogens cannot be eliminated completely. However, could removing the cistern reduce the risk of infection? The alternative to a cistern-flush mechanism is a direct flush system which connects directly to the water supply.
A self-closing valve discharges a predetermined flush volume without the need to store water in a cistern. Direct flush technology uses the system pressure to rinse the pan, so there is no water stagnation, no scale deposits and no build-up of impurities upstream of the flush mechanism.
Direct flush improves hygiene
The Water Supply (Water Fittings) Regulations 1999 require the contents of a toilet pan to be cleared effectively by a single flush of water.2Gravity-fed cistern flush mechanisms may not have sufficient dynamic pressure to ensure a hygienic rinse with a single flush, and a 40 to 60-second refill time can cause additional problems.
Replacing the cistern with a direct flush valve has several advantages in terms of hygiene. Firstly, the flush volume can be adjusted to suit the system’s dynamic pressure and ensure an effective single rinse. Where necessary, the flush can also be adjusted for ecological or smaller children’s toilet pans.
That reduces the aerosol flush plume and prevents unhygienic splashing on the toilet seat and floor, removing the risk of slipping on wet floors. In addition, since there is no refill time, the full flush is instantly available for subsequent users, delivering an effective flush every time.
Hygiene can be further improved by installing an electronic flush mechanism, for example, Delabie’s Tempomatic flush valve. No manual contact is required, so the toilet is accessible to any user, regardless of age, mobility or level of independence.
An automatic sensor detects the user and flushes the valve automatically if they are unable to pass their hand in front of the sensor or if they forget. Furthermore, an automatic duty flush can be programmed to flush the pipework every 12 or 24 hours when not in use, preventing stagnation in the system and reducing biofilm development
Cistern-flush toilets are usually installed through habit but, although they are ideal for domestic usage patterns, the mechanism is not designed to cope with the regular and intensive use experienced in public buildings.
Heavy-handed users can easily break fragile mechanisms. Damage can often occur through voluntary vandalism where the user takes out their frustration on the facilities, or involuntary vandalism where the user is not familiar with the facilities and unwittingly breaks the mechanism. Depending on water quality, watertight seals which are sensitive to scale and impurities, quickly wear out with repetitive use. This inevitably leads to leaks and reduced flushing capability.
According to Thames Water, a leaking toilet can waste up to 400 litres of water a day and a leak in a cistern-flush toilet is very difficult to detect.³ The resulting maintenance is time consuming and problematic, especially where cisterns are installed on frame systems behind IPS panels. However, with a direct flush system, any leak is very easy to identify and remedy.
Direct flush mechanisms, designed for public washrooms, are much more robust. The hydraulic timing mechanism on Delabie’s Tempoflux range of direct flush valves relies on water pressure to operate.
A self-cleaning timing groove reduces maintenance and extends the operational lifespan to over 500,000 activations. Furthermore, the mechanism has standard replacement parts that are easy to access and exchange, simply by isolating the water supply via an integrated stopcock.
Challenging perceptions
Contrary to popular belief, direct flush toilets can replace cistern-flush toilets in refurbishment projects. If the header pipe is close to the installation, only the branch pipe run needs to be changed in the majority of cases.
Although the methodology for calculating pipe sizes for cistern-flush is different to that for direct flush, the pipework sizing is similar due to the principle of calculating simultaneous use.
A direct flush valve activates for seven seconds, whereas cistern refill is between 40 and 60 seconds. Although the effect on demand is cumulative, the shorter duration of the direct flush means that in effect fewer valves will be operating simultaneously. For example, based on a dynamic flow rate of 1.5 litres/second, Delabie estimates that for a block of 20 direct flush toilets, three out of 20 will be activated simultaneously.
Another misconception is that direct flush mechanisms are difficult to install and ongoing maintenance is difficult, especially for recessed applications. Delabie has patented an innovative housing that can be installed on IPS panels or solid walls up to 120 millimetres.
Unlike conventional housings which are cut flush to the wall, this housing features a collar with an integrated seal which provides a watertight seal against the wall finish. The housing can be cut to size in front of the collar and any leaks or condensation evacuate in front of, and not behind or into, the wall. The collar also provides support for the wall actuator plate which conceals the whole mechanism and has an integrated electronic unit for sensor models.
The Tempoflux 3 is supplied in two kits which simplify installation. A preassembled first fix kit means that the housing can be installed and water connections made, system purged and wall finish completed during the first fix.
The second kit includes the actual flushing mechanism which is replaced by a temporary casing during commissioning. Once the system has been purged and the wall finish completed, the flush valve can be installed during the second fix.
The mechanism is fully contained within the housing and can be easily accessed for subsequent servicing. A backflow prevention device is also incorporated within the housing and, in the event of backflow, any water will evacuate in front of the wall.
Conclusion
Direct flush systems offer a hygienic alternative to cistern-flush WCs, reducing the risk of infection in care facilities. Designed for intensive use in public environments, they provide a sustainable solution that manages water consumption, adapting to the usage demands of care facilities, plus they are easy to install and maintain.
Breaking the habit of specifying domestic style cisterns will deliver long term dividends in terms of improved hygiene, sustainability and reduced maintenance.
Contact Details
Telephone: 01491 824449
Email: info@delabie.co.uk
Website: www.delabie.co.uk
LinkedIn: https://www.linkedin.com/ company/delabie/
References 1. Aerosol generation by modern flush toilets, Aerosol Science and Technology, 2013 https://www.ncbi.nlm.nih.gov/pmc/articles/ PMC4666014/ 2. Water Supply (Water Fittings) Regulations 1999, No. 1148, Schedule 2: WCs, flushing devices and urinals 3. Spotting a leaky loo, Thames Water, 2017. https://www.thameswater.co.uk/be-watersmart/you-can-be-water-smart 4. The Building Regulations 2010, Approved Document M, Vol. 2 (2015 Ed.)
