How underground manholes impact infection control
Traditional gravity drainage systems below ground consist of a network of cast iron, plastic or vitrified clay pipes installed with sufficient fall to ensure that wastewater flows from connected appliances to a discharge point. The system depends on correct gradient and precise installation to function as intended.
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In the United Kingdom, such installations are regulated by Approved Document H under the Building Regulations – a mandatory standard for building construction. The document requires that all parts of an underground pipe network must be accessible for inspection and blockage removal.
Similar accessibility requirements apply in most countries, as drainage systems must allow maintenance and clearance of blockages. To meet this requirement, manholes are installed at strategic locations, typically at junctions, changes of direction and changes in level – the points where blockages are most likely to occur.
This access requirement also applies inside buildings. This means that manholes must be located within the building, not only to allow blockage removal, but also for routine inspection of the underground drainage system. In healthcare facilities, this may represent an increased risk, particularly in relation to infection prevention and control.
Risk profile of internal manholes
The risks associated with internal manholes can be divided into two main categories: health and safety, and infection control.
HEALTH AND SAFETY
Internal manholes are expressed at floor level through installed covers. These present several challenges under current health and safety regulations:
- Access must follow an approved procedure and be authorised by competent personnel
- Incorrectly installed or replaced covers may create a trip hazard
- Open manholes during inspection create physical obstructions and require temporary barriers
- Even planned maintenance can therefore affect daily operations.
INFECTION CONTROL
Internal manholes represent a potential infection risk, particularly in the event of a blockage:
- Backflow or leakage may lead to contamination of nearby surfaces
- Decontamination and disinfection procedures must be implemented following leakage
- Annual inspections requiring removal of covers may expose adjacent areas to airborne bacteria and pathogens
- In environments with vulnerable patient groups, this is especially critical.
How vacuum drainage differs from gravity drainage
If internal manholes represent an inherent risk in traditional systems, the question becomes whether the drainage principle itself can be reconsidered. As Kris Wojcik at JETS explains, vacuum drainage changes the fundamentals of how wastewater is transported within a building:
- Vacuum drainage systems operate on a completely different principle from gravity systems. Instead of relying on continuous flow driven by fall, wastewater is transported using controlled pressure differentials - vacuum. The waste is actively conveyed through the system rather than flowing passively through underground pipework, he explains.
This difference in operating principle allows far greater flexibility in how the system is designed and integrated into healthcare buildings. This means that:
- Vacuum systems are not dependent on fall. Pipework can run upwards, horizontally and downwards, independent of natural gradients. This provides significantly greater flexibility in design and installation and allows for more efficient use of space in complex buildings such as hospitals.
- Pipe routing can be integrated into the building architecture. Pipes can be installed in open ceilings, suspended ceilings, within walls – visible or concealed, depending on design and operational requirements. This gives architects and consultants far greater freedom compared to traditional below-floor drainage systems.
- Traditional underground manholes inside the building are not required. By eliminating internal manholes, the associated health, safety and infection risks are also removed. The risk is not only managed through procedures – it is reduced by the system architecture itself.
Better control in healthcare facilities
In healthcare, control is essential – not only over surfaces and air, but also over drainage. Vacuum technology provides a closed and actively controlled system that reduces the risk of leakage and unintended exposure to contaminated or hazardous wastewater. It delivers greater predictability, easier monitoring, and significantly improved control over how waste is handled. The system architecture itself contributes to risk reduction:
- When you remove the need for internal manholes, you remove a potential source of contamination. For hospitals and other healthcare buildings, this means a safer environment for both patients and staff, Wojcik adds.
Infection control through system design
The selection of a drainage system affects more than installation and cost. In healthcare facilities, it can have direct implications for infection prevention, operational stability, and safety.
While traditional gravity systems require built-in access points with associated risks, vacuum drainage offers a system architecture that eliminates them. As infection control becomes increasingly important, the design of the drainage system becomes a strategic decision. For decades, gravity drainage was the default. Today, healthcare decision-makers have a choice – and that choice can directly influence infection risk.