Composting toilet buyers guide

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Tired of flushing water? With care and maintenance, a composting toilet can be a good alternative to the water-loo, writes Anton Vikstrom.

Who has ever pondered what happens when you flush the loo? Apart from thoughts of how much water is chasing your deposit, what about the process downstream? There are alternatives for people to take care of their business on site. While composting toilets have been popular on rural and ‘off pipe’ locations such as national parks for years, increasingly people are interested in composting their sewage on site.

So, what is a composting toilet? How does it work? And how can I get one? This article provides an introduction to composting toilets as well as important information about maintenance.

Sewage treatment today

While the modern sewerage system is an integrated engineered marvel, it is also a marvel of wasteful design. In a standard home in a developed city, all black (toilet) and grey (shower and sink) water is combined, usually in the house slab, before leaving site. From that point it is a long downhill trip to our modern wastewater plants. In Melbourne alone, 330,000 million litres of wastewater are processed each year, including trade waste from industry.

Our centralised sewerage system is a case of out of sight out of mind. Waste is processed at primary level—sieved, screened and mashed up. It passes through a series of ponds where oxygen is circulated to aid microbial digestion of the solids. Water from the system is discharged into oceans or streams after being treated with chlorine. As they say, ‘with pollution dilution is the solution.’ However, releasing this water can cause nutrification, blue-green algae, heavy metal concentration, let alone the negative effect large amounts of chlorine has on ecosystems. Just think how 330,000 million litres of water could be used otherwise.

The other system that operates in ‘off pipe’ conditions is the ubiquitous septic tank (septic being from the Greek ‘septikos’ meaning ‘to make putrid’.) After flushing, all solids settle in the bottom of a large concrete tank and are later pumped out by Mr Wiffy. The excess fluid is disposed of in a sub-surface disposal/leach field. These systems are anaerobic and produce a classic stinky sewage smell. There is no separation of cured waste and fresh waste, allowing direct transfer of any pathogens to the leachate field. While very common in Australia, septic systems are increasingly linked to a number of water pollution issues resulting from a high density of the systems in close proximity to water catchments.

Composting toilets operate on completely different principles from conventional wet systems and offer a proven alternative.

Read the full article in ReNew 104

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