Sustainable plumbing

The greenest systems – from grey-water sinks and rainwater harvesting to composting toilets and solar heaters – save on water and energy
By Elsa Lam

Access to fresh water is a growing global concern. But North Americans continue to consume it as if it were free and unlimited. Canada and the United States use the highest percentage of water per capita in the developed world, placing stress on rivers, lakes and groundwater aquifers.

Old toilets, shower heads and faucets contribute to the problem. Replacing them with efficient fixtures, such as aerating bath fittings, represents an easy, cost-effective investment. Increasingly, these have been engineered to deliver a comfortable flow with dramatically less water.

Second-hand water from laundry, bathing and dishwashing constitutes half of the supply that normally goes directly to sewer systems. With the help of grey-water systems, it can be collected and reused for flushing toilets and irrigating gardens. Grey-water systems range from simple secondary sinks, to more complex installations that collect, filter, purify and redistribute water through a secondary plumbing system.

Harvesting rain is another way to reduce the drain on limited supplies. Rain­water storage cisterns remain an important primary source in many rural, arid parts of the world. Rooftop collection can be implemented in the developed world to provide water for flushing toilets, washing laundry or watering gardens. Rain­water collection in urban areas also mitigates urban flooding by reducing storm­water runoff.

Other innovative plumbing systems trim down heating costs. Solar heaters pipe water through sunlight-warmed rooftop collectors, where it absorbs heat; and water heat exchangers siphon thermal energy from warm wastewater or air conditioning water. In both cases, fresh H20 is preheated before travelling to the water heater, reducing the energy needed to bring it to the desired temperature.

At the other end of the plumbing system, composting toilets reduce, or in some cases entirely eliminate, the massive amounts of water lost to everyday flushing. The waterless, odourless devices are especially appropriate for cottages and cabins with limited septic systems. In recent years, composting toilets have also become an accepted alternative in permanent homes, and have appeared in high-use public facilities, such as along highways and in wilderness parks.

Thoughtfully selected plumbing systems can deliver substantial savings – not only reducing water and heating bills, but also contributing to more sustainable global use of water resources.