The drainage system is often given little thought – we all know it’s there, but as long as we think it’s working it’s very much “out of sight, out of mind”.
In a domestic residence the drainage system transports waste from the bathroom, toilet and kitchen to the sewer pipes of the mains drainage or to a septic tank or similar. Water trap seals are used beneath the sinks (for example within a bottle trap) and within the U-bend of the toilet to maintain a water barrier between the drainage system and the living space.
Protecting Your Living Space From Pathogen Nasties
When the drainage is working properly the integrity of the water barrier is maintained all of the time, even when water is running or flushing through. However, when there’s a problem with the drainage (which could be for many reasons), the water barrier (the trap seal) can become depleted and the barrier is lost. This means that “nasties” within the drainage system can freely enter the living space – these range from unwelcome noxious gases through to extremely harmful pathogens.
A pathogen is a bacteria or virus which can spread disease, including the very well known ones such as Legionnaires’ disease, SARS and the hospital superbugs C. diff and MRSA.
The loss of a trap seal will commonly be indicated by symptoms such as bad smells and noises (gurgling, whooshing or the intake of air). If any of these are experienced we recommend the cause is looked into and rectified as quickly as possible – in most cases, quite simply the installation of one of the Studor AAVs or our combined trap and AAV will solve the problem.
Amoy Gardens Estate in Hong Kong
The tragic outbreak of SARS (Severe Acute Respiratory Syndrome) in the Amoy Gardens estate (Hong Kong) in 2003 provides extreme example highlighting the importance of maintaining water trap seals and preventing nasties from the drainage system entering the living space:
The first person of the outbreak developed SARS symptoms on 14 March 2003. When visiting his brother, who owned an apartment in Block E, at Amoy Gardens that same day he used the toilet whilst he was suffering from diarrhoea. SARS then spread throughout the Amoy Gardens estate at an alarming rate, resulting in 321 infected cases and 42 deaths, with the highest concentration of infections being in Block E.
Research has shown that many SARS patients excrete the virus which causes SARS in their stools. In light of the fact that many residents at Amoy Gardens had been complaining about bad smells for some time, and that many U-traps were found to be completely dry, it is believed that the virus spread through the drainage system and contaminated droplets entered the living space of other apartments, infecting their occupants.
In fact, the World Health Organisation’s Environmental Investigation into the outbreak states that defective water trap seals in the drainage system had been a major contributor to its spread.
As mentioned above, this is an extreme example, but it does illustrate why everything should be done to keep nasties in their place – the drainage system – and well away from the living space!
Further information is also available on this government document which summarises the main findings of the Amoy Gardens Estate Investigation.