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Composting Toilets

June 19, 2001

A public radio commentary

In Vancouver, British Columbia there is a building that people come from around the world to see. For some the trip is nearly like visiting a shrine, others are driven by mere curiosity. The building is the C.K. Choi Institute for Asian Research at the University of British Columbia. It is a striking building of purplish brick, hidden behind rows of young ginko trees. And its roof is made of five magnificent silver arches that look like the billowing sails of a ship. Yet people visit just to see its toilets.

It features flushless, waterless composting toilets. They are completely disconnected from the sewer system, instead the run off is used as fertilizer for the surrounding plants. This might sound like the pit toilet from your camping days, but it's actually a very high-tech cousin featuring rotating tines, temperature and moisture probes and electronic control systems.

What goes into the toilets passes through a system of five trays at the bottom of the toilets' 14-inch stainless steel chutes. Maintenance staff toss in wood chips to aid composting, and red wiggler worms burrow through the muck to turn human digestive by-produce into topsoil.

Any leftover liquids, called composting tea, join the building's used water in a trench along the side of the building, where it's cleaned by micro-organisms on plant roots before being stored for summer irrigation. The system saves more than five hundred gallons of water a day, and eliminates a huge load on the sewage system.

These toilets in the C.K. Choi Institute represent a movement toward a sustainable building. Although the toilets are the most interesting aspect, this idea of sustainablilty was used throughout the building. For example, construction workers made the structure's heavy timber frame with lumber recovered from previously demolished campus buildings. And they reused red brick cladding from Vancouver's streets. The building is very narrow so that each room gets a maximal amount of sunlight. Sensors measure the amount of sunlight in a room, and if it's adequate the electrical lights are automatically dimmed. This makes the building use less than half the amount of lighting of a conventional building.

The five arches of the peaked roof aid the natural ventilation: Air from vents in the lower floors rises to the top of the giant peaks continually flushing fresh air though out the building, and reducing the air conditioning load.

This movement toward constructing sustainable buildings is spreading to homes. People are even retrofitting existing homes to be more green.

You could, for example, put a composting toilet in your home. There are many books and web sites with workshop plans showing all the how and why's of these toilets. You might first, though, wish to make a pilgrimage to the toilets in Vancouver's C.K. Choi Building, because, as one home user warns, "living with a composting toilet is a major [Life] decision."

Copyright 2001 William S. Hammack Enterprises