What is a little used outlet?
Any outlet that is used infrequently or that may be subject to intermittent use is classed as a little used outlet. The definition of “infrequent use” may vary between applications and will depend not only on frequency and duration of use, but also other risk factors, such as water temperature and the vulnerability of the population.
The Health & Safety Executive’s HSG274 Legionnaires’ Disease: Technical Guidance Part 2 states that any outlet “not used for a period equal to or greater than seven days” should be classed as a little used outlet and that “for high risk populations, e.g. healthcare and care homes, more frequent flushing may be required as indicated by the risk assessment”.
The Department of Health’s HTM04-01 Part B: Operational Management states “water draw-off should form part of the daily cleaning process. The procedure for such practice should be fully documented and covered by written instructions”.
HTM04-01 also states “During the temporary closure of wards or departments, a flushing regime should be instigated to maintain system hygiene. Flushing should be continued until stable temperatures are achieved. Advice and guidance is also provided in BSI’s PD855468”. PD855468 states that ‘hygiene flushing’ (i.e. drawing off water for the avoidance of stagnation) should be carried out weekly or “twice weekly in healthcare premises”.
First thing first…
If little used outlets have been identified and the outlets are no longer required then they should be removed from the water system ensuring that all associated supply pipework is removed and that no live dead-end pipework remains left behind.
Where this cannot be achieved a regular flushing programme will be required.
Evidence shows that Legionella bacteria are more likely to colonise the parts of water systems that suffer from a low throughput of water and where water has a tendency to stagnate. HSG274 Part 2 also states that “storage tanks, water heaters, pipework and components and associated equipment containing water” should be “designed to avoid water stagnation by ensuring flow through all parts of the system”. Well-designed water systems can minimise the potential for stagnation by implementing some simple design strategies:
- storage systems and pipework are correctly-sized, with no more than 24-hours storage capacity;
- distribution pipework is as short and direct as possible;
- outlets with an expected high throughput of water are positioned downstream of expected lower use outlets, thus encouraging a regular flow of water to the extremities of the system;
- outlets that are unlikely to be used frequently are excluded from the installation at the design stage;
- consideration may also be given to the use of self-flushing fittings (these must be validated to show they are effective and do not introduce any additional risks).
In any workplace, however, there will often be outlets that are required for operational, welfare or safety purposes where regular and frequent use cannot be assured. In addition, there will be areas that are temporarily out of use. For these outlets, a flushing programme can be an effective means of ensuring that the outlets are periodically operated and that water contained in the associated supply pipework receives regular changeover.
The benefits of regular flushing include:
- Introduction of fresh cold water containing residual disinfectant, either from the mains supply or from a supplementary water treatment system, if fitted;
- Regular exposure of hot water pipework to temperatures at which Legionella and other bacteria are discouraged;
- Disturbance of biofilms through the sheering action of running water.
Process for flushing
Initially a scheme for flushing should be devised. The scheme will form part of the organisations “written scheme of precautions” or “water safety plan” and will need to take account of:
- the responsibility structure for management & execution of the programme including arrangements for holiday cover and absenteeism;
- the technical specification for the task;
- the task risk assessment & safe method of work, i.e. how to flush outlets safely;
- process for identifying little used outlets and keeping the list of outlets under review;
- training requirements for personnel carrying out flushing activities and those supervising them;
- record keeping requirements.
It is commonly asked how long little used outlets should be flushed. Both HSG274 Part 2 and HTM04-01 Part B both advise that outlets should be flushed “until the temperature at the outlet stabilises and is comparable to supply water”. The actual time that this takes will depend on the length of the supply pipework, ambient temperature, frequency of use, localised heat sources, quality of pipework insulation, water pressure, pipework diameter, type and number of inline components etc… the list could go on, but it is sufficient to say that the duration for flushing will vary between installations.
Water emitted from the outlet during flushing should be purged to drain safely. In order to reduce the risk of exposure to Legionella bacteria the British Standards Institutes guidance document PD855468 suggests “flushing should be carried out in a safe manner which minimises aerosol production e.g. removing showerheads prior to flushing”.
HSG274 highlights concerns that lapsed flushing programmes “can result in a critical increase in legionella at the outlet” adding weight to the argument for a clearly documented scheme for the implementation & management supervision of the flushing regime.
HTM04-01 adds that regular flushing applies to all infrequently used outlets and that monitoring water temperature when flushing “may assist in identifying where additional flushing is necessary”.
Operatives carrying out flushing activities should be appropriately trained and supervised.
Do I need to keep records?
Yes. Records may be kept in hard-copy or electronically, either is acceptable as long as certain prerequisites are met. Records should include details of:
- a list of the individual outlets to be flushed;
- the date, time and duration of flushing;
- the initials of the person carrying out the work;
- the water temperature achieved;
- biocide concentration, if applicable;
- any faults and other observations;
- further actions required;
- sign-off by an authorised person.
In addition to the flushing task records, all staff training should be recorded.
How long does a flushing programme last?
For occupied areas checks should be made with local staff to ensure that the list of little used outlets reflects current practices and usage levels. Outlets should be added and removed from the list as necessary. As such a regular review of the scheme and the list of outlets is required to ensure they remain up to date.
Management reporting procedures should be in place to ensure that flushing teams are kept abreast of changes in building and/or department occupancy.
Most readers of this blog will undoubtedly know what little used outlets and may even be aware of aware of some ‘lurking’ around buildings.
It doesn’t sound that difficult to get an outlet flushed routinely to ensure what water turnover. Drawing on our experience, there is never a one fit solution across organisations.
A starting point, it is identifying if you have little used outlets, who can provide you with this knowledge, who is going to be involved in the management of little used outlets, their knowledge and training and finally the process for actually completing the task with reviews in place.
This short video explains how to flush your little used outlet.
Editors Note: The information provided in this blog is correct at date of original publication - April 2018.
© Water Hygiene Centre 2019