WATER SAFETY PROCEDURES
flushing. It has been shown that flushing can help to control Legionella counts from showers, but if flushing ceases, the counts increase beyond those experienced before it started12
(see Fig 3). My
explanation is that flushing selects for ‘sticky’ or ‘flush-resistant’ Legionella. Flushing is a poor compromise compared with normal use of water outlets. The preference is ‘use it, lose it, or flush it’, in that order. There is a popular misconception that if flushing is good, then more flushing must be even better. However, flushing may: n Draw air into the system; n Move sediment; n Rip off biofilm, releasing Legionella into the water phase;
n Re-deposit material elsewhere in the system, e.g. in strainers or unintended sediment traps;
n Reverse the flow in hot water return pipes (even in the presence of a functioning return pump);
n Flatten calorifier temperatures; n Draw the contents of stagnant storage tanks into service.
Flushing in response to the COVID shutdown The European Society of Clinical Microbiology and Infectious Diseases (ESCMID Study Group for Legionella Infections) has published guidance19
8000 7000 6000 5000 4000 3000 2000 1000 0
Figure 4. ‘Controlling’ Legionella in hot water with twice-weekly flushing and six-weekly disinfection?
bad enough, but each week the 10% positive samples are typically from different outlets. This appears to show that biofilm, nutrients, and Legionella are being distributed around the water systems.
Is automatic flushing better than manual?
for
managing hospital water systems during the COVID-19 pandemic, which references evidence from China,20
which showed that
approximately 50% of COVID-19 fatalities had experienced a secondary infection, suggesting that patients are at increased risk of such infections while in hospital, and for several months after recovery. Inevitably, the Society’s guidance includes a recommendation for the flushing of infrequently used outlets. This same group has also published guidance for nursing and care homes,21 systems,22
dental water and other buildings.23
Sectors other than healthcare, such as offices and educational institutions, have implemented flushing regimes for the most awkward of buildings, namely those which are not closed, but remain partially occupied. At the time of writing I am dealing with such a building, a student hall of residence which usually accommodates hundreds of tenants, but had only a handful of residents during the coronavirus shutdown. An over- enthusiastic flushing programme, (with outlets being run for up to 30 minutes, partly in an attempt to achieve tank turnover) has resulted in air being drawn into the systems, calorifier temperatures being flattened, and sediment disturbed. Consequently, despite weekly disinfections and a more careful flushing regime, there have been 10% of the weekly samples yielding Legionella results of up to 30,000 cfu/L, which would be
60 Health Estate Journal November 2020
There is a recognition that if flushing is required, there are potential drawbacks to manual methods, such as: n ‘Busy’, ‘important’, or lazy people fail to carry out their flushing duties;
n The reproducibility of the flushing regularity, frequency, duration, and flow rate, will potentially be poor;
n Tick-boxing, whether on paper or electronically, to say that flushing has been done when it hasn’t;
n Misunderstandings over the technique required for flushing.
There is also the difficulty in determining a definitive list of the outlets which are infrequently used, and therefore require flushing, and their distinction from unused outlets which should be eliminated. The following websites provide examples of commercially available flushing systems for water systems, taps, and showers. These are examples, not recommended suppliers, nor any form of endorsement: n
https://www.kemper-uk.com/building- technology/product-information/khs- drinking-water-hygiene/khs-hygiene- flush-box
n
https://www.radacontrols.com/en/ products/all-products/rada-sense- washbasin-t3
n
http://www.safepurge.co.uk/ safepurge.php
As with any technique or technology, care needs to be taken before the adoption of an automatic flushing system. The first problem is that the installation of an automatic flushing system implies
permanence, which is an admission that there are root causes which are to be controlled, rather than eliminated. The Control of Substances Hazardous to Health Regulations,24
which apply to
microorganisms such as Legionella and Pseudomonas aeruginosa etc, require risk assessment and consideration of elimination in preference to control. It follows that automatic flushing systems should not be installed without first undertaking and recording a suitable and sufficient water safety risk assessment. There are potential pitfalls with automatic flushing systems, including impacts on patients: n When a patient is on the lavatory in a wet-room type bathroom, an automatic flushing shower tends to be unwelcome;
n Automatic flushing of outlets may disturb a patient’s sleep;
n Mental health patients can be upset by automatic systems of any kind, because they give the impression that inanimate objects are ‘alive’.
The potential benefits of automatic flushing are the opposite of the drawbacks of manual flushing listed above – notably reliability, reproducibility, and lower cost. However, in common with manual flushing, automatic systems can mask fundamental water system shortcomings rather than address them.
Conclusion – Is flushing a failure? The mantra ‘sweat your assets’, not commonly heard in healthcare, would be decreasingly applied to sanitaryware and fittings in healthcare premises. I’ve never seen a queue at a washbasin for handwashing, whether patient, staff, or visitor. The consequence of this is that the healthcare estate has infrequently used outlets, which have grown in number with the fashion (and I chose the word
Legionella cfu/L
24/04/2020 01/05/2020 08/05/2020 15/05/2020 22/05/2020 29/05/2020 05/06/2020 12/06/2020 19/06/2020 26/06/2020 03/07/2020 10/07/2020 17/07/2020 24/07/2020 31/07/2020 07/08/2020 14/08/2020 21/08/2020 28/08/2020 04/09/2020 11/09/2020 18/09/2020
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