Hospital wastewater (HWW) is characterised by the presence of various emerging contaminants, such as pharmaceutically active compounds (PhACs), several microorganisms, including antibiotic-resistant bacteria (ARB), Carbapenemase-producing Enterobacterales (CPE), antibiotic-resistant genes (ARG), and persistent viruses, etc. It is important to note that Carbapenem antibiotics are often considered a last-resort treatment, as they represent the final suite of antibiotics available. However, increasing bacterial resistance to them underscores the urgent need for antibiotic stewardship.
Healthcare is a rapidly growing industry, as medical treatments become more sophisticated and more in demand due to the increasing incidence of chronic disease. I will be exploring the following.
- Water Safety Groups: are we aware of wastewater risk to patients, and how are we controlling the processes?
- Water Safety Plan documents, including wastewater vigilance.
- How can we reduce the risk of contaminants from wastewater to patients?
- Hospital clinical waste and wastewater, and how to manage contaminates safely.
- What preventative strategies are available to mitigate the risk from wastewater?
Wastewater and sewers — The superhighway for the movement of organisms across a healthcare setting
I would like to begin with the acknowledgement to Professor Joachim Kohn,1 who has explored his interest in pathology, and was the ‘inventor extraordinary to the Medical Laboratory’; he died in London on 31 March 1987. Born in Poland in 1912, he qualified in medicine there in 1936, served in the Polish forces, and became a prisoner of war in Russia until 1941, being one of the few officers to survive the Katyn massacre. He continued to support the war efforts, and when he moved to the UK, he served bravely in the British 8th Army throughout its campaigns until 1947. In peacetime he became a ship’s surgeon for two years before training at St Mary’s Hospital Roehampton, where he became a Consultant Clinical Pathologist in 1955, and later a Senior Lecturer in Chemical Pathology at the University of London, officially retiring in 1977.
You may ask yourself why I have mentioned this highly driven and altruistic man, and what connection could he possibly have with wastewater and drainage contamination. Professor Joachim Kohn invented a device known as the ‘Kohn trap’ to thermally disinfect sink traps in 1970.2 This was to aid the disinfection of the domestic wastewater system at the point of discharge (washhand basin drain). At the time of his invention it was not recognised that microbial contamination could possibly be passed on to patients from wastewater contaminates.
Unfortunately, many years later, the tragic neonatal outbreak of Pseudomonas aeruginosa in Belfast in 2012 forced change in the way we think about contamination of domestic water systems and water outlets such as complex taps, including possible cross-contamination from splashback from drains and the wastewater systems. Tragically, four babies died from an outbreak of Pseudomonas aeruginosa in Northern Ireland — one died at a Londonderry hospital, and three others in Belfast. Due to this event the Department of Health issued the first HTM 04-01 Addendum: Pseudomonas aeruginosa — advice for augmented care units, in 2013. The guidance recommended significant change in the way we adopt water management across healthcare in high-risk areas such as augmented care wards. The requirement to conduct Pseudomonas aeruginosa testing of the domestic water in healthcare was initiated, and this continues today.
Remedial action and regular re-sampling
The Pseudomonas aeruginosa sampling regime identifies contaminated outlets which must be addressed through remedial action, with a continuing need for a strict re-sampling schedule to ensure that outlets are clear of Pseudomonas aeruginosa bacteria before they are returned to clinical use. This process requires vigilance — not only from the mechanical aspect of water management for waterborne pathogens such as Legionella risk assessments covering the configuration of domestic water distribution systems, but also in terms of input from all members of the Water Safety Group in relation to the clinical risk assessment. There needs to be wide-ranging involvement from all responsible for water management as part of their duty of care to ensure that patient safety is paramount.
Testing in line with HTM 04-01
Healthcare domestic water systems, especially in high-risk areas, are frequently tested in accordance with the HTM 04-01 guidance to ensure that we are one step ahead of any possible contamination. However, I would question whether focusing on the water discharge point alone is sufficient to ensure that transmission to patients is eliminated? We all know that handwashing performed at a handwash station — an interface between water and drainage — provides an important barrier to cross-infection systems. However, the associated hazards from the drainage system go largely unnoticed, and yet a large percentage of washhand basin drains are heavily contaminated with P. aeruginosa. It is well recognised that within healthcare, reports of outbreaks linked to distribution water systems outside of neonatal units are over-represented by multi-resistant organisms, and increasingly by carbapenemase-producing organisms (a group of bacteria) — germs which produce carbapenemases (enzymes) that destroy antibiotics called carbapenems.
Designs that promote or disturb drain biofilm, misuse of sinks, and placement of patient care materials adjacent to sinks, have all been associated with sink-related infections. It is not unusual, as part of remedial works, for Estates Department engineers to have to remove contaminated pipework at considerable cost, and with some disruption to clinical activity. Much could be done to improve current thinking and practice on domestic water system design, and the placement and use of healthcare water assets. The ‘NTM addendum’ is a supplementary document related to Nontuberculous Mycobacteria (NTM) disease, and provides guidelines, particularly in the context of healthcare or public health (NHS Estates Technical Bulletin (NETB) No.2024/3). It recommends not incorporating 90-degree bends in water or wastewater pipework, as these increase the risk of blockages, corrosion, and scaling, which adversely affect system flow and temperature controls.
Other potential areas for improvement and positive actions towards controlling contamination include a preference for us of waterless or low-water-use solutions in augmented care settings where possible, and placing washhand basins at the entry to high-risk areas, preventing unnecessary risk of proximity to patients. Another potential step could be implementation of augmented care washhand basin area zones — for example incorporating different-coloured 0.5 m zones around sinks to discourage placing items within the area that can be cross-contaminated and passed on to patients by contact. Screens, or raised washhand basin sites, would also help.
Hospital design must take into consideration patients’ safety, functionality, and be practical. The practical part often falls under the influence of human behaviour. Water Safety Group members play a key part in ensuring that all aspects of water management — including managing wastewater — are overseen and managed in accordance with current guidance and regulations. Inappropriate actions of staff, patients, and the public, and the placement of unnecessary items at water outlets, play a big part in contamination spreading. For example, simply ensuring that clinical sinks and washhand basins (CWHBs) are used strictly for handwashing, and that no items are placed on or near a drain (such as placing patient water jugs directly on the sink base or drain when filling them), will help to prevent cross-contamination. Staff should also ensure that shower outlets are correctly tethered (as per water regulations), and never left to lie on the shower base, especially over the drain. Equally, fitting shower drains in an offset position to prevent patients from standing directly on them is also good practice.
Multidisciplinary group’s knowledge
Water Safety Group members hold a wide range of knowledge, with the ‘WSG’ being a multidisciplinary group formed to commission and develop an organisation’s Water Safety Plan (WSP) document, providing a detailed approach to comprehensive strategy to ensure that water is safe for all types of use — from the conception of a building water system, and associated equipment, through to its demolition. The Water Safety Plan should thus cover all aspects of water risks and how to address them, including wastewater control. Currently, there are no clear Planned Preventative Measures (PPMs) in place for drain maintenance other than as set out in HTM 04-01.
BS 8680:2020 Water quality. Water safety plans. Code of practice3 clearly states that risks from wastewater should be considered. However, the Code of Practice is not widely implemented across healthcare, and such action should be included as part of a comprehensive Planned Preventative Maintenance programme.
Appropriate control measures, communication, and training, should always be implemented to minimise these risks of contamination. All healthcare staff involved in water management should be aware that the use of sinks to dispose of patient secretions, for example, has been associated with sink colonisation, and environmental surface contamination from CPE. Selective pressure from antibiotic excretion in the urine and faeces has been proposed as a potential contributor to the success of multidrug-resistant organisms in hospital plumbing.4 The WSP should include measures to prevent ingress of this type of cross-contamination, and should also consider the proposed guidance in healthcare. For example, the prevention of contamination should also include the avoidance of splashing during the use of washhand basins, by maintaining clear zones of at least 0.5 m around the basins, and/or incorporating screens. Currently this is not being observed due to the restricted space in clinical areas.
Hospital outbreaks
HTM 04-01 Part C references the multidrug-resistant Pseudomonas aeruginosa outbreaks in two hospitals and the association with contaminated hospital wastewater systems.5 The outbreaks occurred in two English hospitals; each involved a distinct genotype of MDR-P.
One outbreak was hospital-wide, involving 85 patients, and the other limited to four cases in one specialised medical unit. The source of many such infections is unclear, although there are reports of hospital outbreaks of P. aeruginosa related to environmental contamination, including from tap water. The investigation and intensive sampling highlighted, as possible causes of contamination of the clinical areas, faulty sinks, shower tray (poor drainage) and toilet design, clean items being stored near sluices, and frequent blockages and leaks from waste pipes. The investigation went as far as to suggest that the blockages were due to paper towels, wet wipes, or improper use of bedpan macerators.
The outbreaks highlight the potential of hospital waste systems to act as a reservoir of MDR-P and other nosocomial pathogens.6 Multidrug-resistant (MDR) and extensively drug-resistant (XDR) Pseudomonas aeruginosa are frequent causes of serious nosocomial infections that may compromise the selection of antimicrobial therapy. This is particularly important in patients with cystic fibrosis (CF), who may be chronically colonised, and suffer from recurrent infections and disease exacerbations due in part to the limited efficacy of antipseudomonal agents. Multidrug-resistant organism infections are hard to treat, because they do not respond to many common antibiotics, even the most powerful ones. However, certain antibiotics can still help control MDROs in most people. The doctor will try to find the type of MDRO causing the illness, which is essential in selecting the best antibiotic. Treatment with the wrong antibiotic can slow recovery and make the infection harder to cure.
Steps which we can begin to take to reduce the risk and implement control measures include replacing sinks with easier-to-clean models less prone to splashback, educating staff on reducing blockages and inappropriate storage, reviewing cleaning protocols, and reducing shower flow rates to reduce flooding. It is equally important to be vigilant, and to report risks to the right personnel to undertake corrective measures to reduce microbial spread of contamination.
Today we have the opportunity to ensure that any new hospital building design and specification takes into consideration wastewater, not just from a clinical and patient safety standpoint, but also in terms of climate change impact, and mitigation and reduction of the carbon footprint. Careful consideration must be given at the design stage to the functionality of water outlets in the healthcare setting (augmented and intensive care units). The Infection Prevention and Control team needs to work closely with the Water Safety Group and Capital Project team to ensure that the following factors are being taken into consideration):7
n Measures to control the spread of microorganisms in healthcare premises include handwashing, but also the regular use of antimicrobial hand-rubs, as this can result in a significant reduction in the use of washhand basins. Under-use of taps encourages colonisation and growth with Pseudomonas aeruginosa, Legionella, and other waterborne organisms. The design team should be aware of this, and accordingly consider how local infection policies regarding hand hygiene and the use of antimicrobial hand-rubs might impact on the frequency of use of washhand basins, and the volume of water being distributed.
- The most effective management of showers will be achieved via the removal of unnecessary ones and the regular use of others.
- To prevent water stagnation, check for infrequently used outlets — assess frequency of usage and — if necessary — rarely used outlet(s). For example, the provision of showers in areas where patients are predominantly confined to the bed, and the resulting lack of use, could lead to stagnation.
Augmented care locations
Augmented care settings should be carefully designed to ensure the correct positioning and number of water outlets installed, to prevent the additional risk to patients from outlets in close proximity to the patient, especially if the outlets are ‘low use’, creating water stagnation and risk of microbial contamination. Seldomly used outlets need to be put on flushing regimes (prevention of bacterial load and waste of wholesome water), which can be implemented via mechanical auto flush. However, more often than not such regimes are implemented by manual action, which is ineffective from both a time and cost standpoint, and very difficult to monitor.
Furthermore, water use has a direct association with climate change mitigation. Significant amounts of energy are used in the heating, supply, and treatment of water. Water UK (2007) estimates place the carbon costs of water supply at around 0.271 grams of CO2 per litre, a figure likely to be much higher if the water is heated. More efficient use of water in healthcare facilities could therefore result in a significant reduction in their carbon footprint. Managing water efficiently across the healthcare estate will require a wide range of approaches — one of which could be a revision in the correct amount of water outlets installed, based on risk and possible usage. Infrequently used outlets or redundant ones — due, for example, to a change of a use from a clinical space to a storage area, will create the need for frequent flushing implementation. As water prices increase, so too will the need for careful water management and stewardship.
It is clear that good water management, including effectively managing clinical waste and wastewater, has a huge impact on patient safety, as well as an environmental impact.
Managing clinical waste
As well as addressing the challenges and risks associated with water outlets and drainage in healthcare settings, we must also look to the overall management of clinical waste. NHS healthcare providers produce approximately 156,000 tonnes of clinical waste annually that is either sent to high temperature incineration (HTI), or for alternative treatment (AT), which is equivalent to over 400 loaded jumbo jets of waste. This has a significant environmental impact, and is associated with both high running costs and carbon emissions.
The NHS England Clinical Waste Strategy, published on 7 March 2023, sets out NHS England’s ambition to transform the management of clinical waste by eliminating unnecessary waste, finding innovative ways to re-use, and ensuring that waste is processed in the most cost-effective, efficient, and sustainable way. Therefore, the potential benefits of a combined on-site hospital wastewater and mixed waste treatment platform system designed to address the pressing need for sustainable waste management in healthcare settings should be investigated.
By deploying advanced technology and techniques, innovative systems can effectively remove pharmacological, biological, chemical, microbiological, and micropollutant contaminants, including drug-resistant pathogens, thereby mitigating environmental and health risks. The approach prioritises patient care while delivering positive impacts on clinical, environmental, and economic fronts. The integration of precautionary measures and automation reduces human error and minimises contact moments, enhancing safety and efficiency. This approach is available through several companies, and is already in use. Now, more than ever, the healthcare sector is required and expected to treat and care for patients while also contributing to a sustainable environment.
Eliminating clinical waste on site, and having the ability to control discharge to the sewer, will prevent contamination. Any discharge to the sewer, other than domestic water, must have the prior agreement of the statutory responsible bodies. Anybody intending to dispose of any waste to the sewer that may present a substantially greater risk of damage to the sewerage undertaker’s assets than domestic sewage should first seek advice from the sewerage undertaker. HTM 07-01: Safe and sustainable management of healthcare waste guidance,8 states: “The Controlled Waste (England and Wales) Regulations give legal definitions of ‘clinical waste’ and ‘offensive waste’. Such wastes are regulated due to their toxicity, hazardous nature, and capacity to do harm to human health or the environment. This regulation sets out a statutory obligation to ensure that the waste is managed appropriately to prevent harm.”
In summary, key to the preventative strategies to mitigate the risk from wastewater is the approach and attitude of the personnel responsible, a clear understanding of how wastewater and clinical waste are removed and disposed of, and an acknowledgment that, where possible, prevention is better than cure. Preventing inappropriate and unnecessary discharge of contaminates into drains will reduce both waterborne pathogen proliferation and contamination of sewer systems. Even more importantly, understanding the importance of avoiding fouling of drains will reduce the increasing risk from antibiotic-resistant bacteria in healthcare settings.
Further reading
- Environment and sustainability. Health Technical Memorandum 07-04: Water management and water efficiency — best practice advice for the healthcare sector. Department of Health, 20 March 2013. Updated 26 January 2024. https://tinyurl.com/y8h6rpmv
References
1 Past Lives. Journal of the International Federation of Clinical Chemistry 2003; 14(1): 40-41. https://tinyurl.com/u2npbsyj
2 A waste trap sterilising method. Kohn J. The Lancet 12 September 1970; 296(7672); 550-551. https://tinyurl.com/55uamf3y
3 BS 8680:2020 Water quality. Water safety plans. Code of practice. bsi, 30 May 2020. https://tinyurl.com/bd9tsrnu
4 Park SC, Parikh H, Vegesana K, Stoesser N, Barry KE, Kotay SM et al. Risk Factors Associated with Carbapenemase-Producing Enterobacterales (CPE) Positivity in the Hospital Wastewater Environment. Appl Environ Microbiol 2020 Nov 24;86(24)
5 Breathnach AS, Cubbon MD, Karunaharan RN, Pope CF, Planche TD. Multidrug-resistant Pseudomonas aeruginosa outbreaks in two hospitals: association with contaminated hospital waste-water systems. J Hosp Infect September 2012; 82(1):19-24. https://pubmed.ncbi.nlm.nih.gov/22841682/
6 Coyne AJK, Ghali AE, Holger D, Rebold N, Rybak MJ, Therapeutic Strategies for Emerging Multidrug-Resistant Pseudomonas aeruginosa. Infect Dis Ther 2022 Feb 12;11(2):661—682. https://pmc.ncbi.nlm.nih.gov/articles/PMC8960490/
7 Health Technical Memorandum 04-01: Safe water in healthcare premises: Part A — Design, installation and commissioning and Part B — Health Technical Memorandum 04-01: Safe water in healthcare premises — Part B: Operational management.
8 HTM 07-01 (2023 version): Safe and sustainable management of healthcare waste. Updated 7 March 2023. https://tinyurl.com/bwd999fu