As countries move in and out of alert levels in response to the COVID-19 pandemic, we are seeing multitudes of buildings being vacated for significant periods of time before they are reoccupied at a later date. But what does this vacant period mean for building services, and what do you need to think about before reoccupying your building?

During a lockdown period, several buildings services systems may have been left idle, leading to both health and safety and maintenance risks. In New Zealand, an article released by MBIE (Ministry of Business, Innovation and Employment) shortly after alert level 3 was announced, cited water stagnation and depleted water seals within plumbing systems as potential sources of health risk. In the article MBIE recommended thoroughly flushing water supply systems and replenishing water seals prior to building reoccupation, noting that specific flushing procedures will need to be developed for larger buildings.


The challenge 

During normal building operations, water is consistently being drawn off for drinking and sanitisation. This allows both fresh water to be drawn into a system as well as discharge, to replenish water seals at fixtures, floor drains etc. This consistent introduction of fresh water into a plumbing system helps maintain the system as potable water. The discharge of water into the drainage system maintains the water seals, preventing foul air (sewer gases) from entering the building.

During a lockdown period the lack of water movement in both these systems can present health risks through a number of factors, which include: 

  • Bacteriological growth 
  • Pathogens 
  • Biofilms 
  • Heavy metal concentration (lead, copper, etc.) 
  • Release of sewer gases into the building 

The longer buildings sit idle, the greater the likelihood one of the above (or similar) risks becomes present in the system. 


The solution 

Before buildings are reoccupied, they should have their water systems flushed and disinfected, and their drainage systems water seals replenished, to assist in maintaining the health and safety of all building occupants. 

While not specifically identified in MBIE’s article, mechanical cooling towers may need to be disinfected and ventilation filters checked for bacteria prior to recommissioning the mechanical systems. With a number of these systems being controlled by BMS, you may be able to do some of this work remotely before entering the building.

We have been working closely alongside a number of building owners, tenants, facilities management teams, maintenance staff and plumbing professionals to assist in developing testing, flushing, and disinfection plans for a number of buildings across New Zealand as they look to reopen. 

If you have any queries or would like to find out more, please don't hesitate to contact Brendon Dwyer or Nik McIntosh below.

About the Author
Nik McIntosh

Senior Associate – Building Services

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