Monday, May 08, 2006

Water. Too much, too little or just right?

An interesting conversation again is happening at Thom's Board from above link about family farms and that the present industrial farming system will collapse. Why?
-- Sustainability.
It's a systems concept, which means it's not linear. Which means it fills up a blackboard in a hurry with circles filled with words, and arrows pointing to the circles and all sorts of mind scrambling visuals that don't fit into a Post A Reply window.

So instead of looking at every possible connection of how a system will collapse, I want to break it down to manageable components to discuss here. And of course one of the most important issue is water. This post is just going to look at some alternative ways to store/retain rain water.

The first link is to an "This Old House" special on This Roof Resists Hurricanes, Collects Water.
The thing about living in paradise is there's always a catch. In the case of Bermuda, where This Old House has been filming the renovation of a 200-year-old Georgian house, hurricanes hit the small mid-Atlantic island summer and fall, toppling trees, rattling shuttered windows, and peeling off roofs. Oh, and then there’s the absence of any fresh water source on the island. As a result, Bermuda’s roofs have evolved over four centuries to do two things: protect houses against gale-force winds and funnel whatever the heavens rain down into large cisterns that feed household taps. By law, every house must collect 80 percent of the water that falls on its roof.
The result is a strong, nearly self-supporting structure that holds its own against the weather while sending clean water into the tank. It’s the best and cheapest way to supply fresh water — up to 30 gallons per person are needed per day — to the 60,000-plus residents of this tiny island nation. It's also what accounts for Bermuda's signature white rooftops, perfectly placed amid the palms and set off by the pastel houses for which the island is famous.

Next is for another island (Key Westers) that has access to a supply of water but wants to save water and thus money to have it piped in, at Water Conservation Conch Style
For one, collected rainwater is ideal for irrigation--why pour potable water, at $5.20 per thousand gallons, out on the monkey palm? Some estimates claim irrigation accounts for nearly 40% of water use in Key West, so easing that load would leave a large proportion of the 14 million gallons of piped-in water the island uses each day back in the Everglades aquifer where it belongs.

Another benefit: Cisterns catch water that would otherwise become storm-water run-off--rain that falls, washes the island's building, streets and parking lots, and then needs a place to go. Currently, most of that greasy, dirty water ends up in the ocean, where it is implicated in killing off the living reef that surrounds the Keys.

But of course there will be some are always areas of concern...
Although many were destroyed as anachronistic and breeders of mosquitoes after the Navy's pipe came in, there are still 353 cisterns of record on the island. Old Henry Flagler, builder of the railway that linked Key West to the mainland, put a million-gallon one beneath his Casa Marina Hotel back in 1922, and it's still being used to water the grounds. Good enough for Conchs and capitalists, the cistern seems to be an old idea that's coming back.

The next link is a very useful guide for setting up cisterns/catchments at:1.1 Rainwater harvesting from rooftop catchments. I only want to add the concerns here at present.
· A procedure for eliminating the "foul flush" after a long dry spell deserves particular attention. The first part of each rainfall should be diverted from the storage tank since this is most likely to contain undesirable materials which have accumulated on the roof and other surfaces between rainfalls. Generally, water captured during the first 10 minutes of rainfall during an event of average intensity is unfit for drinking purposes. The quantity of water lost by diverting this runoff is usually about 14l/m2 of catchment area.
· The storage tank should be checked and cleaned periodically. All tanks need cleaning; their designs should allow for this. Cleaning procedures consist of thorough scrubbing of the inner walls and floors. Use of a chlorine solution is recommended for cleaning, followed by thorough rinsing.
· Care should be taken to keep rainfall collection surfaces covered, to reduce the likelihood of frogs, lizards, mosquitoes, and other pests using the cistern as a breeding ground. Residents may prefer to take care to prevent such problems rather than have to take corrective actions, such as treating or removing water, at a later time.
· Chlorination of the cisterns or storage tanks is necessary if the water is to be used for drinking and domestic uses. The Montserrat Island Water Authority constructed a non-conventional chlorination device with a rubber tube, plywood, a 1.2 m piece of PVC tubing, and a hose clip to chlorinate the water using chlorine tablets.
· Gutters and downpipes need to be periodically inspected and cleaned carefully. Periodic maintenance must also be carried out on any pumps used to lift water to selected areas in the house or building. More often than not, maintenance is done only when equipment breaks down.

Of course maitenance levels depends on what it will be used for as in if only irrigation then chlorine is likely to be overkill.

And now closer to home at Harvest the Rain.
Wrangle water from the sky for watering, washing and even drinking, no matter where you live.

Adapted from Environmental Building News

Rainwater harvesting systems can be as simple as directing gutters to a lidded garbage can or as complex as a concrete cistern, roof washer and filtration system. But whatever your application, rest assured that you'll be getting some of the purest - and cheapest - water around.
But after it falls from the sky, rainwater percolates through the earth and rocks, where it picks up minerals and salts. As Heinichen points out, in many cases, this water also collects other contaminants such as industrial chemicals, pesticides and fecal coliform bacteria found in the soil. Captured before it hits the ground, rainwater is free of many pollutants that plague surface and underground water supplies and, according to the Texas Water Development Board, "almost always exceeds [the quality] of ground or surface water."

Rainwater typically has very low hardness levels, which reduces the use of soaps and detergents, and eliminates the need for a water softener. Fewer minerals also saves wear and tear on your plumbing fixtures.

Now there can still be contaminants in the rain water but as far as acid rain, this should not be a problem for many people other than the east coast and most notably in the North East. On this map at National Water Conditions look for areas that have less than pH 5 as the article Acid Rain spells out.

More Links of Interest:
International Rainwater Catchment Systems Conferences
Save Family Farms, Save America



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