Public Health Internal Drainage Standards

Rod Green
Engineer
The Environment Group, Liverpool

More countries across the world are facing water management challenges due to climate change, increased urbanization and population growth. The world’s population is currently around 7.5 billion and is projected to rise to within 10 billion by 2050. Our cities are expanding worldwide, and buildings are getting taller and more complex. This creates new challenges for the design and installation of building services, in particular internal wastewater drainage systems. A minimum of 50 millimeters, and in many cases 38 millimeters of water, is all that protects internal environments from potentially harmful sewer gases and particulates. Air pressure fluctuations within these systems need to be better managed locally to prevent water trap seals being compromised.

There are a number of regional and national standards and codes that are used around the world to provide engineers with guidance on the design and installation of drainage systems. Unfortunately, these codes typically rely on the use of pre-determined tables and formulae based on steady-state (continuous flow) fluid hydraulic calculations. In modern day buildings, the internal wastewater drainage systems are anything but steady and are very random. The existing standards in use today are also out of date. Many of the tables and formulae are based on low- and medium-rise buildings, and the majority of them have not been reviewed and updated to ensure optimum performance in today’s challenging high-rise built environments.