Building sewage systems face overhaul in Sars threat

Drainage in buildings may have to be overhauled because of the danger of spreading the Sars virus through lavatories.

A study by a research group at Heriot-Watt University in Edinburgh has found evidence to indicate that airborne viruses can break through the water seals of drainage systems and spread through a building.

The researchers found that the disease can breach the water traps in sinks, basins, gullies and WCs that are designed to isolate a drainage system from a room.

There are also fears that bio-terrorists could exploit this knowledge to spread a virus from room to room using the drainage system.

Lynne Jack, a research fellow in the department of building engineering and surveying at Heriot-Watt said: “Airborne contaminants could be transmitted to a different room via the drainage system.”

The findings were presented at a conference hosted by CIBSE and the Institution of Civil Engineers on designing terrorproof buildings.

The danger was first highlighted after a computer drainage simulation model was developed at Heriot-Watt. This indicated that Sars could have been spread through cross contamination in drainage systems at the Amoy Gardens development in Hong Kong.

Jack said it was known that the Sars virus could be spread through fecal matter – this was the suspected transmission route in Hong Kong.

She said: “Using this model it was possible to propose a method to help analyse what happened with the spread of Sars in Hong Kong”.

Jack warned something similar could occur if a surge in the flow in a sewerage system caused the pipes to become full and force air to move back up the system (see diagram).

The study called “Simulation and analysis of cross contamination routes due to the operation of building drainage and vent systems” is directed by professor J Swaffield and Dr Lynne Jack.

• Chris Veale, a government security adviser at MI5 and the man responsible for counter-terrorism measures in government buildings said the government was examining ways to increase security in its accommodation.

He said: “The government is currently looking at including radiological and chemical protection measures in its buildings”.

He said enhanced scanning equipment would be installed at the entrance to a building. Veale made the announcement at the CIBSE/ICE joint conference on Building Security against the Threat of Terrorism.