Community Interest – January 2010

Napa Valley Marketplace Magazine “Community Interest” January 2010.

Water, Water, Everywhere…
But Will There Be Enough To Drink?

While there seems to be an adequate supply of affordable and accessible water to fulfill our local needs, the truth is that locally and globally, water is quickly becoming the new gold. While water makes up 80% of the earth’s surface, only 2% is fresh (or potable).  Most of that 2% is locked up in glaciers and ice caps.  While a standard goal for us is to use 80 gallons of water per day or less, we use 100 – 125 gallons per day on average.  Sure, we consume some of this water via food and drink but most of it becomes greywater (kitchen, shower, sink, washing machine and laundry waste) or blackwater (toilet and garbage disposal waste) and simply goes down the drain.  To help capture, conserve and use water wisely, two strategies are gaining in popularity:  rainwater harvesting and greywater reuse.  Here’s a quick overview and some local resources.

Rainwater Harvesting
Think about it.  Rain – when we get it – is free.  Rainwater harvesting is simply intercepting rain run-off and putting it to good use.  Systems are relatively easy to create. Rainwater falls onto a roof surface; gutters capture the water and divert it to downspout; the downspout connects to a tank (or cistern) were it remains until used.  For irrigation, a tank at ground level or raised slightly is sufficient water pressure and you shouldn’t have to filter it.  You can add a pump if you need more pressure.  More elaborate systems, especially those designed for interior use, might include multiple tanks with filters, pumps and controls.

So, how much can you collect?  One inch of rain on 1,000 square feet of roof yields some 600 gallons.  See the Calculation Sidebar to measure your potential. The cost of a tank depends on size – a 575 gallon container can cost up to $575, while a 3,000 gallon is about $600.  As of October 2009, City of Napa water rates ranged from $4.05 to $6.14 per 1,000 gallons depending upon location and elevation and we can expect rates to continue to rise.  To learn more about water conservation at visit the City of Napa Water Division website at

Greywater Capture & Reuse
Despite traces of dirt, food, grease, hair, and certain household cleaning products, greywater can be reused for non-potable purposes, like irrigation and washing the car.  Not to be confused, blackwater is what has come into contact with fecal matter and shouldn’t be reused under any circumstance.  Learn more about waste water treatment at

Greywater can be controversial and a little complicated, but it has potential for significant water and money savings.  It’s been estimated that a typical household can save 22,000 gallons/year by capturing and reusing laundry greywater alone.  For perspective, one square foot of lawn uses about 30 gallons/year.  A simple laundry-to-landscape system costs a few hundred bucks.  Learn more about how to plan your system at  Last fall, in response to ongoing drought conditions, California decided to revise its state greywater standards and allow the installation of basic systems without a permit.  However, because this is a recent development and requirements vary – check in with your local jurisdiction and the Napa County Department of Environmental Management ( before investing time and money.

How Much Rainwater Can You Collect?
Multiply your collection surface area by the inches of annual rainfall to get your annual cubic feet of water.  Divide your annual cubic feet of water by 7.43 to get your gallons per year.  For instance, a 1,000 SF roof getting 28 inches of rain/year will provide 17,337 gallons/year.

Fixtures – Fix or Replace?
If a leak produces 10 drips per minute, it can waste 43 gallons per month.  At 120 drips per minute, the loss goes up to 518 gallons – so, fix the leak.  If the faucet is old, it might be better to replace it.  While you’re at it, consider upgrading your toilet.  If you have an older toilet, switching it out can reduce water use by as much as 54%.  Check with your local water department, they might even give you a rebate.  Looking to upgrade your fixtures? Visit the Green Room at Steve Silva Plumbing – 901A Enterprise Way, Napa.  707-252-3491

In addition to local resources, learn more by visiting:
California Urban Water Conservation Council –
North Bay Water Reuse Authority –
Department of Water Resources –
California’s Water Conservation Resource –


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