What Causes the Problem?
Most marine toilets are flushed with seawater or river water which is drawn from a hull fitting below the waterline. All owners of leisure craft and smaller commercial craft are familiar with the odour problems associated with these toilets.
There are two main reasons for the odours:
- The sea or river water drawn into the system contains living organisms which rapidly die and decompose due to lack of oxygen and light in the pipe work (or sanitation hose). Anaerobic bacteria take over and create foul smelling sulphurous gases and other compounds, which are then drawn into the toilet bowl during the flushing process and then released into the atmosphere inside the craft. This is particularly evident when the boat has not been used for a while.
- The flexible pipe work (or sanitation hose) used to plumb marine heads is made of expanded flexible PVC. Bacteria from both the seawater and the urine and faecal matter deposited in the toilet can, over time, penetrate and live inside the structure of the PVC. So the outside of the sanitation hose running through the bilges of the craft can also become continuously malodorous.
Although it is possible to partially improve the problem by putting disinfectant into the toilet bowl, this is immediately flushed away with the next flush of the toilet and the bacteria can take over again. More importantly, this does not disinfect the flushing water being drawn into the toilet bowl from the sea or river and this is the area where some of the worst odours arise.
Some owners incur great expense by having all of the sanitation hoses on their toilets and holding tanks replaced but within a short period of time the bacteria are back, along with the odour.