Wet & healthy03 June 2019

Who knew the humble tap could kill? OE takes a look at water safety in healthcare and how it should be managed

According to Marlow-based water treatment specialist WCS Group, NHS Trust Water Safety Groups have a tough job ensuring holistic management of water hygiene and that their response to risk is fit for purpose.

WCS Group’s critical services marketing director, Chris Abraham, says the risk to health from waterborne pathogens such as Pseudomonas aeruginosa, Stenotrophomonas maltophilia, Mycobacteria and Legionella is difficult to manage, as some of these bacteria naturally occur in water. Potable water supplied to homes, businesses, industry and hospitals, via the mains, is treated to remove any pathogens that may be present at the treatment works. A small amount of chlorine is left in the water to maintain quality as it travels through the network of mains and pipes delivering water to consumers. While healthy people’s immune system can normally cope with low levels of bacteria, in healthcare establishments, they pose a real and serious threat to already-immune compromised patients, highly susceptible to infection.

In April 2018, Chartered Institution of Building Services Engineers (CIBSE) held a symposium on water safety in healthcare. It highlighted that while hospital water safety systems are safer now than 20 years ago, old pipework, cold water storage tanks, scale, mixer taps, little-used outlets, dead legs, tap aerators, flexible hoses (now banned for use in healthcare premises, due to synthetic linings harbouring bacteria) and water supply management are all threat factors that must be regularly monitored and assessed, to minimise risk.

The main source of official guidance on providing safe water in healthcare premises is published by the Department of Health (DoH) in the form of its Health Technical Memorandum 04-01. The latest version was updated in 2016 following new guidance from the Health and Safety Executive.

The latest version aims to move healthcare providers towards a holistic form of management of water safety by the establishment of water safety groups (WSG) and implementing water safety plans (WSP). It promotes best practice and covers the key areas WSGs must consider when designing, installing, commissioning, operating and maintaining water services in healthcare premises.

The guidance highlights the need for robust governance and management, outlining the remit of the WSG and how this relates to the provision of safe water.

It says key criteria and system arrangements must be in place to help stop the ingress of chemical and microbial contaminants, colonisation and proliferation. The guide includes information on temperature regimes for sanitary outlets to maintain water hygiene; ensuring the safe delivery of hot and cold water; how the correct selection of system components and correct use by occupants can help preserve the quality and hygiene of water supplies, and it provides a point of reference to legislation, standards and other guidance pertaining to water systems.


The guide contains an overview of some of the different water systems (including specific detail on components) and their safe installation, commissioning, operation and maintenance, and it provides technical guidance for typical system layouts and individual components.

In particular, the tap outlet aerator has become a major focus for concern. A study published in the February 2014 issue of the journal of the Society for Healthcare Epidemiology of America, showed that research found significantly higher levels of infectious pathogens in water from taps with aerators compared to water from deeper in the plumbing system. The study said that researchers from the University of Genoa in Italy studied cold and hot water samples at two tertiary care hospitals for a year from taps used by healthcare professionals. The study assessed growth of bacteria at both the tap and deeper within the water distribution system. Cold and hot water sampling was carried out first with the aerators in place, and then after disinfecting and flame-sterilizing the outlet point and letting the water run for two minutes, to analyse the microbiological features of the plumbing system. Researchers found the total microbial load was up to 10 times greater when aerators were in place than after sterilisation and flushing.

Other specific areas considered high risk include interruptions in water supply. This can increase the risk of microbial ingress, especially if these result in depressurisation of supply pipework. Water system design should ensure that sufficient reserve water storage is available to minimise the consequence of disruption, while at the same time ensuring an adequate turnover of water to prevent stagnation in storage vessels and distribution systems.

Measures to control the spread of microorganisms in healthcare premises include the regular use of antimicrobial hand-rubs. This can result in a significant reduction in the use of hand-wash basins. Ensuring water is run regularly to flush out dead legs is an important part of water safety management.

The disinfectant residual in the mains water supply can also have implications. Under certain conditions, some water companies alternate the residual levels of disinfectant in the mains water supply and the type of disinfectant used (for example, chlorine and chloramine) between winter and summer. Healthcare providers should consider the installation of secondary disinfection equipment within their own premises to ensure the safety of supply.

WCS Group’s Chris Abraham says that his company has produced its own guidance for WSGs. The document states that WSGs should follow a set of fundamental principles, the first being that no healthcare operation is risk-free, and health risks can only be accepted if proven to be very low. In particular, WSGs must approach water safety as a collective responsibility. General awareness of the threat and risks must be made mandatory, and a level of competence must be maintained through training and by the use of outsourced support and partnering with external hygiene specialists.

BOX OUT: Water safety plan

Its purpose is to understand what plant, equipment, and assets are on site, their interdependence, and the holistic operating risk that they pose. WCS Group advises WSGs also consider the below:

● Up-to-date and fit-for-purpose schematics should describe all visible and hidden assets, systems and pipework layout. They should be reviewed regularly.

● Hazard analysis and critical control points, designed for preventing risk and identifying hazards, should be embedded into management strategy.

● Physical control measures include temperature, flushing, materials, ultraviolet, tap design, filtration, dead-legs, old or obsolete equipment. Chemicalmeasures include: chlorination, chlorine dioxide, monochloramine, copper-silver ionisation, hydrogen peroxide, titanium advanced oxidisation processes.

● Operating limits for water treatment must be put in place and recorded. They will influence decisions about asset life cycle, maintenance, refurbishment or removals and secondary disinfection decisions. Parameters include: Time, temperature, dose, pH, water hardness, water consumption, energy consumption, age and complexity of equipment and site, accuracy and frequency of data.

● Once control measures have been put in place, system performance and KPIs need to be monitored.

● Monitoring and consistently recorded data will enable better decisionmaking, more timely asset life cycle management, and less reactive maintenance, unforced shutdowns and less operating risk.

● According to law, records must be retained for five years.

● System validation and verification through analysis of performance data.

Peter Shakespeare

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