Waterharvesting's Blog

Getting the most out of gray (grey) water and rainwater harvesting

How will Arizona find 100% more potable water in the next 30 years?

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It is fascinating to correlate states that have commenced water harvesting code development (graywater and rainwater) against their population growth rates.

Here is a chart (from google.com) showing population growth over the last 30 years for selected states:

Link = http://www.google.com/publicdata?ds=uspopulation&met=population&tdim=true&dl=en&hl=en&q=population+usa#met=population&idim=state:04000:01000:06000:12000:32000:35000:48000:53000:49000:13000

So while the population growth for the US averages about 1% per year (over the last 30 years), California had 54% growth, and Arizona 132% growth!

While there is scope for saving water in existing homes – currently Tucson residents average over 140 gallons per day in personal water use, compared to 40 gallons per day personal water use in places such as Melbourne, Australia, it will not be an easy path.

Aggressive water saving initiatives within the home will help – water efficient appliances, showers, change in habits etc; in warmer states over approximately 60% of personal water use is external (ie irrigating the garden, washing cars etc.

At some point authorities will have seriously tackle the water issue. The US economy relies on real growth, not debt growth, and will falter unless infrastructure can support the growth.

Certainly politicians are beginning to take note, with attempts to promote water re-use, although once the code actually hits the ground competing interests fight for turf.

Water Purveyors do need to sit back and work out how they are going to support this growth without massive impost on the consumer. Several purveyors now find they do not want water to be saved at the home – they need every drop to fulfill water reclamation contracts (ie water treatment) that are already in place. Examples of this are parts of Nevada and Arizona. This would be fanatastic if the reclaimed water was being used sensibly, however in many cases the water is simply re-used on golf courses and sporting grounds.

Even if the re-claimed water is presented back to the home, the intial sales pitch was your home could now have a guaranteed supply of water for the garden, at minimal cost. So instead of encouraging home owners to conserve this reclaimed water, the water purveyor wants them to use as much as possible, so they can improve the bottom line.

Drainage enginners don’t want you to use less water, because they are concerned you will be too efficient and cause flushing issues within the sewer and storm networks. It would make sense to design new subdivisions with this in mind. As I mentioned in the previous post, common sense and reality dont always come together.

If you live in one of the states listed on the chart, I recommend visiting your local water purveyor, and ask  how they plan to cope with growth for the next 30 years, based on the past 30 years. Let me know what you find out.  The many dicsussions I have had across the country are worrying.

What we do know is there is no more water to be found in the Colorado basin. Even if global warming is a non event, there will not be a 50%+ increase in rainfall over Western USA to support growth.

Hats off to Tucson Water and the City of Tucson. Their code requiring compulsory greywater stubouts on new houses is a great start. They have much more work to do developing a framework and impleneting the policy but they are on their way.

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