WATER SYSTEM HYGIENE & SAFETY
all cistern-flush mechanisms allow for complete renewal of the full 9 litres of water in the cistern. One alternative is to remove the cistern entirely, and replace it with a direct flush technology. This cistern-less flush system connects directly to the water supply, using the mains pressure to flush the pan without the need to use any stored water. Hygiene can be further improved by installing an electronic sensor-controlled model, which will flush automatically every 24 hours after the last use. Those electronic models, which incorporate a piston- operated solenoid valve, also ensure that all the water in the valve is renewed with every flush. Cistern-less flush technology can be
installed in refurbishment projects as well as new-builds. 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. For example, a direct flush activates
for 7 seconds, whereas cistern refill is between 40 and 60 seconds. If multiple toilets are flushed, the effect on demand is cumulative, resulting in system pressure drops. However, the shorter duration of the direct flush means that,
Direct flush technology removes the need for standing water in WC cisterns.
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, 3 out of 20 will be activated simultaneously. Cistern- less flush technology therefore helps to reduce the system pressure imbalances which can cause cross-flow.
Carole Armstong
Responsible for marketing and communications for the UK market, Carole Armstrong has worked for Delabie – which claims to be ‘European market-leader in taps and hygiene sanitaryware’ – for 14 years. Initially located at the company’s head office in northern France, she is now based at the UK office in Wallingford, Oxfordshire. With over 14 years’ experience in the commercial washroom sector, she specialises in the healthcare sector, and is responsible for media relations, events, and technical translations for the UK market.
78 Health Estate Journal October 2023
Inconvenient conveniences Another disadvantage of cistern-flush toilets is that they are prone to leaks. They are ideal for domestic usage patterns, but often the mechanism comprises plastic components that cannot withstand the usage patterns experienced in public buildings. Heavy-handed users can easily break fragile mechanisms, and the seals – which are sensitive to scale and impurities – quickly wear out with repetitive use, especially in hard water areas. This inevitably leads to leaks, which are not always visible, and reduced flushing capability, which may be seen as an inconvenience, but may not be reported by users.
Wastage from leaking toilets According to Thames Water,5
a leaking
toilet can waste up to 400 litres of water a day, and a leak in a cistern-flush toilet is silent and not always obvious. 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, the mechanism is robust – designed to withstand 500,000 operations. Any leaks are very easy to identify and remedy. Designed for intensive use in public environments, cistern-less systems will reduce water consumption, reduce the maintenance burden, and lower the risk of Legionella infection.
The findings of the ECDC highlight the
ever-present risk posed by Legionella in healthcare facilities. The report suggests that focusing on the design, infrastructure, and regular maintenance in water distribution systems will reduce the incidence of Legionnaire’s disease. As time and budgetary concerns place increasing pressure on Estates and Facilities teams, manufacturers need to provide solutions that will support the ECDC’s recommendations and reduce that burden. Product designers can offer creative solutions to engineering challenges, such as low-volume interiors and cistern-less systems, which will reduce, and even eliminate, standing water in water control mechanisms. There is also no need to compromise on patient safety, since advances in thermostatic technology can deliver anti-scalding safety while maintaining infection control without the need for onerous maintenance.
References 1 Increasing rates of Legionnaires’ disease in the EU/EEA, European Centre for Diseases Prevention and Control. 3 July 2023. https://tinyurl. com/3du842vm
2 Health & Safety Executive, Legionnaires’ disease Part 2: The control of legionella bacteria in hot and cold water systems. 2014.
3 Department of Health HTM 04-01: Supplement. Performance Specification D 08: thermostatic mixing valves (healthcare premises). 2017 edition.
4 Li Y-Y, Wang JX, Chen X. Can a toilet promote virus transmission? From a fluid dynamics perspective. Phys of Fluids 2020 Jun 1; 32(6): 065107.
5 ‘Water saving tips’. Thames Water.
https://www.thameswater.co.uk/help/ water-saving/water-saving-tips
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