Dry Conservancy

The dry conservancy systems which were put forward as serious alternatives included dry closets, pan systems and pneumatic systems.

The dry closet or earth closet, named in contrast to the water-closet or flush toilet, did not use water to wash away the excrement but rather was a means of collecting the solid excrement in a container. The addition of earth, ashes or charcoal after each visit to the closet deodorised the excrement which was periodically collected at night by cart and taken to a processing plant where it was dried out for use as manure.

The pan system consisted of having a pan under the toilet seat which was collected by night-men at regular intervals and replaced with an empty one. The pan was able to take urine as well as faeces and did not require the use of earth for deodorising. One version of the pan system was described at an 1889 meeting of the Engineering Association of NSW by E. W. Cracknell. A collection pan would be fitted to the toilet seat forming an air-tight joint which would prevent the escape of noxious gases. The full pans would be carted to a Poudrette works where the pans would be emptied, washed out mechanically and returned with a measure of deodorant. This would overcome the nuisance and disease that was spread when pans were not cleaned out and would eliminate the need for householders to have to cope with ashes or dry earth.

At the poudrette factory the night soil would be strained. The liquid would be chemically treated to remove the ammonia and then passed into the sewer whilst the solid portion was dried to make cakes of manure called Poudrette. Such a process was already in operation at Botany at the premises of the NSW Poudrette and Ammonia Company and, he claimed, produced no unpleasant smell and the poudrette was sold at a profit as fertiliser.

The first pneumatic system or vacuum system was merely a means of emptying cesspits using air power rather than hand labour. Later Captain Liernur developed a pneumatic system for transporting dry wastes through pipes by means of a partial vacuum created in those pipes. The waste products would be sucked to their destination. It was argued that Sydney was ideally suited to the Liernur system because of its small depth of soil and the consequent difficulty and expense of excavating through solid rock to enable water-carriage sewers to follow the necessary straight lines and gradients that a gravity dependent system requires.

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