Treehugger at Rainwater Harvesting Workshop

We attended Toronto's rainwater harvesting workshop this morning, looking for the answer to the question- why bother when we are beside a freshwater lake and can just pump more? a) The answer- infrastructures for pumping and cleaning water are not growing as fast as the population and we cannot pump it fast enough.

Dr. Peter Coombes of the School of Environment and Life Sciences talked about the Australian experience, where around Sydney they have a similar problem. 10 years ago all of the water companies said "don't worry, we have lots of water" and now there is a crisis, and Australians are returning to rainwater harvesting. Points made:

-Rainwater harvesting takes a huge load off existing mains water supply infrastructure;

-only 5% of water in a home is used for drinking and cooking, so if you have any concerns about drinking rainwater, don't- you still can use rainwater for everything else;

-Rainwater harvesting reduces stormwater runoff (a huge problem in older cities with combined sewers)

-and in fact, where many claim that rainwater is unsuitable for urban water supply, it is often safer than City water. 3.2 million Australians dring rainwater and there have only been a few cases of gastrointestinal illness, whereas sewage contamination sickened thousands in Victoria, 400,000 in Milwaukee (where a hundred died) and thousands in Walkerton Ontario (where 7 died). Analysis in health publications indicates that it is over 1000 times more likely to conract illness from mains water than it is from rainwater.

We note that in an earlier post today, an underground tank was being installed for a Tacoma homeowner. Dr. Coombes recommends above ground tanks to avoid the possibility of contamination from septic tank overflows.

Next up, Dr. Hari J. Krishna of the Texas Water Development Board, discussed RWH in Austin, Texas.


Dr. Krishna points out that if if RWH is used for only 15% of residential landscape irrigation in the US, it would save a billion gallons of water per day. For every inch of rain, about 600 gallons of water can be collected from 1,000 sq.ft. of roof area.

A typical home with 2000 sq.ft. of roof area in Central Texas can yield up to 40,000 gallons a year, water that would otherwise run off and contribute to erosion. If properly managed, the RWH system can provide up to 100 gallons of water per day for a typical home. The cost of a RWH system depends on the size of the cistern used for
storage. A RWH system for a home can cost anywhere from 5,000-$8,000, which includes the guttering for leading the water to the cistern, costs for the cistern, pump and treatment system.

by [LA]

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