Here, in the third in a series of articles running in HEJ this year on hospital wastewater systems, Steven Van De Peer, an Authorising Engineer (Water) at Tetra Consulting, discusses what he believes are ‘some of the opportunities for the UK to lead in such systems’ design’. He warns that the only way to eliminate the risks associated with drainage systems in the healthcare environment is to entirely remove the services.
I should begin this article by emphasising that the potential solutions put forward in the piece have not been trialled, and are intended to encourage further consideration of how to tackle some of the problems and issues around healthcare water systems.
Design
There are many potential design issues with modern (and older) drainage systems from an infection control perspective, and – as with all risks – we must first discuss elimination, before we move on to reduction and so on. The only way to eliminate the risks associated with the drainage systems in the healthcare environment is to entirely remove the services, including the drainage services, along with the sanitaryware and the water supply pipework. In very high dependency and high-risk environments, it may be beneficial to reduce the number of handwash stations and water services in general to the lowest possible number, while also ensuing that there is a strong design strategy in place that identifies the best placement for handwash stations and other water services within a ward area, ensuring that the proposed activity within the space is the driving factor.
Adoption of HBN guidance
HBN documents currently create an issue with regard to the adoption of water-free / minimal water care. These documents are often quoted by designers and operational staff. Patient safety must be at the heart of design, and as such, with antimicrobial resistance approaching, the total adoption of documents like the HBNs needs to be curbed, and a more focused approach to clinical design implemented. The removal of services to a practical minimum will actively remove potential contamination reservoirs within a ward area, thereby limiting the retrograde contamination that is possible. This also benefits maintenance, space allocation, and the general practice as regards particular outlets, as there are fewer available, potentially leading to very specific uses
World’s first ‘water-free care’
ICU A scientific paper published in 2017 in Antimicrobial Resistance and Infection Control1 described what was said to be the world’s first water-free care ITU (see Figure 1). This was not a new-build designed for water-free care, but a refurbishment. With the New Hospitals Programme underway, if ITUs were to consider the benefits of water-free / minimal water care, this may have a significant impact and saving on design / construction
In terms of risk reduction, the segregation of drainage systems is a concept that must be evaluated and heavily considered within the healthcare environment, although it is likely to only be a concept that could be applied to refurbishment and new construction, rather than retrofitting into areas currently in use
Drainage systems containing faecal matter
Any drainage system that contains faecal matter should be heavily considered for segregation from all other drainage systems. It may be beneficial to create separate drainage systems in the following categories:
Faecal waste.
Clinical handwashing and shower drains (perhaps further segregating high dependency / high risk areas).
Kitchens.
Clinical process.
Other uses
In this way, the drainage systems would be entirely separate, and not connected in any way, apart from at the point of entry to the main sewer. This will not eliminate all issues, but may prevent backflow issues, and the majority of cross-contamination between drainage systems, particularly if backflow prevention devices are installed at the point of entry to the main sewer
Segregation of systems will only be possible through standardisation of the pipework in use; for example it should be very clear what drainage pipe is connected to what system – therefore colour coding of drainage system pipework, or mandatory labelling, would ned to be considered at industry level. The installation of sweeping bends should be actively designed into a building for all drainage systems, allowing for appropriate space to install them. Ninety degree bends slow the velocity of the water, and reduce the ability of the drainage system to move debris through the pipework dramatically, and while sweeping bends will not eliminate drain blockages, they will reduce instances of blockage
‘Strategic placement’ of vertical stacks
The strategic placement of vertical stacks to accommodate as short a drainage run as possible is a solution that needs careful consideration. Fewer vertical stacks will result in some drainage services being run over long distances, and this increases the potential for blockages, with debris having more chance to slow down through increased friction over the distance. An increase in vertical stacks may significantly impact the design of a building or area, as more services space will be required. If drainage systems are separated, this may also result in numerous new vertical stacks of varying sizes to accommodate the various services. The route that a drainage pipe takes is of equal significance, and should never pass over key clinical areas such as pharmacies or food preparation areas.
The locations of the stacks are often defined by the architectural layout, but is this backwards thinking? Can we allow for the architectural layout to define the lowest practicable risk? Hospitals need to be architecturally laid out in tandem with risk reduction strategies for the infrastructure. Materials of construction, particularly in healthcare, are important. Plastic piping is cheap and easy to install, but has more susceptibility to biofilm growth, and it may be beneficial to consider the use of copper waste traps to assist with reduction of biofilm at the periphery of the drainage systems.
Sanitaryware design
The design of the waste system pipework is of great importance, but equally important is the design of the sanitaryware, and not just for handwash stations. In fact all sinks / basins within a healthcare environment should have similar IPC considerations applied to them.
Splashing is, of course, a major issue in healthcare, due to the ease with which organisms can escape from the sink / basin and get into the environment. More consideration indeed needs to be given to dispersal. With evidence that – depending on the design – splashes from washhand basins can travel up to two metres, the installation of splash guards should be heavily considered. Especially where space is an issue, and sinks are placed next to drug or food preparation areas, physical separation of these areas is likely to be beneficial.
Specific sinks provided
Where the filling of receptacles is required, specific sinks should be provided for this type of activity, and other miscellaneous clinical practice. Crucially these sinks should be equipped with flip-down brackets for placing a receptacle onto, to avoid placing it in the sink, potentially directly on top of a drain. Bacteria can transfer to the base of the receptacle, and then be easily transferred to other surfaces.
When designing new installations, a set distance should be considered for installing any surface from any washhand basin, unless the basin is intended to form part of a continuous process – for example in a kitchen. In this instance, the splash guards would be more practical. Often in the healthcare environment, due to the unavailability of space, rooms are repurposed or are given multiple purposes, which often results in the storage there of sterile equipment and other clinical resources. If these items are within the splash zone of the sink / basin, they can become contaminated, offering another potential transmission route.
Back-draining basins
Back-draining basins, while a clever idea to avoid water discharging directly onto a drain, may have their own setbacks. When water flows onto the basin and the water stream splits, it can create an area of suction at the point of entry to the drain where the two water streams meet. This has the potential to pull contamination back into the sink from the entry to the drain. The design of the back-draining basin needs to be considered further, as it may be more beneficial to have an offset vertical drain with a diffuser. While this approach will certainly have its own problems, it is likely to assist in preventing sink blockages, and will also ensure that water outlets do not discharge directly onto the drain. This would apply to all sinks / basins within a healthcare environment.
Shower drains
In the same vein, we need to consider shower drains, which are are often placed directly underneath patients. They can then become contaminated and easily move this contamination around the clinical environment. Shower drains should be designed to be far from where a patient is intending to stand, and also to be easily accessed and maintained with minimal blockages. In this respect, trough drains with long diffusers should be considered to allow water to flow consistently, and permit easy access to the underlying drain for cleaning and maintenance
Drainage systems are often forgotten. They are mostly concealed within building fabric, and are predominantly made from plastic, making them easier to assemble. While the main underground drainage systems are for the most part installed by competent persons, a great deal of above ground drainage connections from sanitaryware and connections into stacks show evidence of poor installation. The main issues as regards quality of installation are time, budget, training, and the appropriate management of people.
Construction and MEP projects are almost always undertaken against very tight time constraints, particularly within the NHS, and this general lack of time can result in corner-cutting. It will almost always be the perceived ‘nonessential services’ that will suffer, and drainage systems are often impacted by this unfortunate process. Budget is a very similar issue. In terms of all the systems required in a healthcare scenario, drainage will surely be seen as of a lower priority, compared with medical gas pipelines, water services, electrical, and fire services etc. With budgets often tight, compromises need to be made, and drainage services are often high on the list of services that can be downgraded in expense, either through quality of design, materials, or competent install
Factoring in the ‘people factor’
Beyond the general issues of time and budget that affect all projects by some measure, there is the people factor that needs to be considered. Drainage system installation is not considered in the sector as a skilled job, and in fact the installation of above ground drainage connected to services is not exclusively carried out by appropriately trained plumbers, and – even when it is – the risks posed by drains within a healthcare environment are not well communicated.
Appropriate training on the risks associated with drainage, and poor installation within healthcare environments, are issues that need to be raised at industry level, and such considerations should ideally form part of all plumbing apprenticeships / vocational courses. For the risks to be minimised throughout the project process there are many factors to consider; people management, and monitoring of installation quality are key. These would traditionally be part of the job of the Clerk of Works – a role that has diminished in popularity through the NHS over the years but – when implemented appropriately, with well-defined process and sufficient knowledge of the risks versus the intended design – can be extremely effective in reducing poor practice and deviation from design.
Protecting exposed drains
Throughout the installation process, there should be an emphasis on the protection of all exposed drains, while water systems should not be charged with water too early, and should be leak tested using compressed air. This will both allow for the drains to remain closed for elongated timeframes throughout installation, and reduce the need for flushing of little used outlets until the water system commissioning phase begins
Exposed drains, including toilets, washhand basins, and sinks, should be plugged or bunged using the appropriate means (not rags or paper towels) to prevent debris and building dust or other waste entering drainage systems until they are close to hand over. Underground drainage systems should also be protected from ingress of building debris.
Commissioning
The aim of the commissioning process should be to ensure that the drainage system is installed as designed, operates as expected, and is clean and ready to be put into use.
All drainage systems should ideally be leak tested. After all, a main purpose of the drainage system is to isolate the waste from the environment, and any leaks should be identified before handover of a system, and be remedied before normal operation starts.
The flow rates of the drainage systems should be checked against the intended design, and any deviation of these flow rates to the stacks, and to the main ground sewer, should be investigated, since they could be evidence of poor installation, or debris being present in the pipework. Before drainage systems are handed over for use, it may be considered good practice to use remote cameras to verify that the main sewers at ground level are appropriately clear. This – along with leak testing and flow rate data – will provide some assurance of a suitable drainage system.
Handover
The handover process should be conducted over a period of time, and the drainage systems should be a topic to be discussed. The handover process for drainage should (as with most other systems) include the delivery of an O&M manual describing the systems that have been installed, the manner in which they have been installed, the intended purpose and design intent, the correct operation of the systems in relation to the design, the correct maintenance practices to ensure continued efficacy of the systems, any maintenance access points, and any relevant commissioning data.
The drainage systems should also ideally be ‘witnessed’ by key stakeholders, and the main design concepts discussed; in this way the systems can be seen in person, questions can be raised, and those that will have responsibility for the systems’ day-to-day management will understand the basic layout and operation concept.
Occupation and ongoing maintenance
Once the wastewater system is in use, it is important to make sure that all users are made aware of the intended use of the basin / sink. This is predominantly an education issue, but may be assisted with specific signage on the intended use, while in newer building designs, differentcoloured IPS panels could be considered to create a colour-coded approach to usage. Effective planned maintenance of wastewater systems requires considering regular monitoring with cameras in predetermined locations following a risk assessment. This can be beneficial to ensure that the systems are kept free from debris long term to prevent large-scale blockages.
Blockage-clearing equipment storage should be considered in line with a risk assessment that considers IPC. The movement of this equipment through the hospital environment, and its potential cleaning and disinfection, are also key considerations – the means for which should be established and reviewed.
Response times to blockages should be carefully considered, not just on the severity of the blockage, but also the location. A big blockage that has seen an X-Ray department completely blocked needs a rapid response, as indeed would a blocked sink in an augmented care ward. Both the operational impact and the risk to patients need to be considered when applying appropriate response times to maintenance activities.
The process of returning basins/sinks back to normal use will require thought, as a blockage dramatically increases surface contamination, and when the blockage has been rectified, the basin surfaces will need to be disinfected to avoid further retrograde contamination of the area and protect the water systems.
Communication to staff
The communication of the various risks to all staff that interact with the drainage system or provide care is an element that is severely lacking. The potential problems associated with healthcare wastewater infrastructure require awareness at all levels, in all departments, right across the sector. There needs to be a bigger and more inclusive engagement programme across the NHS regarding AMR, with the drainage system risks on the agenda – from design, right through to ongoing interactions. The UK has the opportunity to save thousands of lives and lead the way in new hospital design framed around AMR and patient safety, and indeed the New Hospital Programme, and the sector as a whole, must take account of the risks posed by drainage in healthcare to drive new practices and innovation at industry level, or the price could be very high indeed.
Steven Van De Peer
Steven Van De Peer EngTech, TMIET, MWMSoc, AMIHEEM, is an Authorising Engineer (Water) at Tetra Consulting, with a history of working in the construction and facilities management industries since 2005, across multiple sectors, including healthcare, education, government, and commercial. He has extensive experience in domestic, evaporative cooling, spa, and swimming pool water systems.
Reference
1 Hopman J, Tostmann A, Wertheim H, Bos M, Kolwijck E, Akkermans R et al. Reduced rate of intensive care unit acquired gram-negative bacilli after removal of sinks and introduction of ‘water-free’ patient care. Antimicrob Resist and Infect Control 2017; (6)59. DOI 10.1186/s13756-017-0213-0