Microbiological aerosols in drainage systems

Abstract

Drainage codes exist to provide appropriate and safe means of disposal of effluent from buildings. If it is seen that those codes may not be written in a way which leads to an assured appropriate outcome, then they need to be questioned. Accordingly, this thesis follows up on the author's concerns regarding the approach taken to the layout of drainage under today's building regulatory regime. Under the New Zealand Building Code any standards may be used or any approach may be taken to methods of building, drainage and plumbing, providing the approach used can be justified as complying with the non-prescriptive objectives and performance requirements of the Building Code. Under this approach drains are now being installed more often under buildings with their maintenance access points within the building. This situation, and the consequent likely emission of microbiological aerosols, are cause for concern: that is the airborne release of microscopic particles. The "Report of the Departmental Committee - Intercepting Traps in House Drains" of 1912 from the UK, parts of which are quoted in Section 7.0, reinforced these concerns of the author. But these concerns were not shared by many others who have a major influence on the form and shape of our buildings, and it was assumed that current code requirements may not have been based on any significant research. Based on a relatively widespread lack of knowledge, there was a scenario of doubt and denial as to whether or not there were shortcomings in current code requirements in New Zealand. This provided incentive for the research project within this thesis, on the basis that there may be encouragement for future code requirements to be based on even more research in order to confirm their validity. This thesis demonstrates that the ambiguity in existing approved methods of compliance with current building codes fails to adequately protect the populace from adverse potential health effects.