Rainwater Harvesting: Old Idea, Modern Usage
WOULDN’T it be wonderful if we hadthe means to provide pure drinking water tohomes and schools in rural communitieswhere water scarcity or contaminations aresevere problems? Or to construct hotels, villasand resorts along the Guanacaste coastlinethat were self-sufficient for their potablewater needs?These things are possible and they arebeing done routinely in other countries usingan age-old method, as refined by modernmaterials and engineering techniques. Themethod, called Rain Water Harvesting (orRWH for short), has been used by theAmerican Indians in Arizona for at least athousand years and now, its time may havefinally come to Costa Rica and CentralAmerica.As water rates increase (this year AyAwas granted a 36% increase after requesting58%, with more increases pre-approved fornext year) and as scarcity becomes a moreevident reality (AyA says supply problems inthe San José area will arise in 2006 if it doesn’tget $300 million to reinforce and expandits systems), more and more people in theCentral Valley, not to mention coastal andrural areas, may turn to RWH as a means toassure themselves of adequate supplies ofpure water.One couple, Carlos Walker and MaylingCharpentier, are early advocates of this technologyand possibly early victims of thoseAyA predicted supply problems.The couple’s home, located in SanAntonio de Escazú, southwest of San José, iscut off from water service every day duringthe dry season and sometimes well into therainy season.DESPITE living at the edge of a raincatchment area, from about 7 a.m.-5 p.m. theWalkers, and the remainder of their community,lose their water service daily, apparentlyto ensure adequate supplies for other customerslower down in the valley.“After years of having water only atAyA’s convenience as one their ‘swing’ customersand one bad incidence of illness fromcontaminated water, we’re looking forwardto putting AyA to work as our ‘swing’ supplier,only when we need them,” Walkersaid.To achieve that end, the Walkers areretro-fitting their existing roof, gutters, storagetank and small water pump to collect,store and deliver rain water to their home.The rainwater is abundant where they live,but seasonal, so the key to providing sustainablewater to their home is the additionof more storage capacity, mosquito/vectorproof fittings and appropriate filtering systems.With these additions, the naturally softenedand pure rainwater that falls on theirroof will become their primary source ofwater. To further improve their water situation,they will also collect rainwater off alarge shed in their back yard and even theirgarage.THE water from the garage will not betreated for potable uses, instead it will gostraight to watering the herb garden andfront yard areas via a simple drip irrigationsystem, whereas the shed at the back of theirproperty will provide water for the rear yardand numerous fruit trees on the property. Ifadditional water is ever needed for the yard,the Walkers are reserving the option ofdiverting their ‘graywater’ to the garden.The graywater, if recycled in this way, willprovide year-round underground irrigationto their yard every time they take a showeror brush their teeth, leaving only the ‘blackwater’from toilets and kitchen sinks to continueto go to the septic system.The Walkers aren’t the only early advocatesof RWH.Nat Grew is president and founder ofdesign and construction company GrupoBonario, which specializes in providingturnkey services to wealthy individualslooking for their piece of paradise along thecoast of Nicoya or Guanacaste Province, butwith a strong commitment to sustainabledevelopment and minimal environmentalimpact.In the areas where Grew’s customerswant a home, water is typically in limitedsupply, at least from the typical groundwatersources. However, these coastal areas haveabundant rainfall and are therefore thehomes are ideal candidates for RWH systems.Whereas a costly new well, whichrequires a permit, may produce brackishwater, or not yield the desired quantities offresh water, the rains are much more predictable,and the quality is unmatched byutility or groundwater sources.Grew’s affinity for offering his client’sthe RWH option is driven by both practicaland environmental concerns.“When we add a RWH system we knowthe customer will enjoy adequate and purewater supplies every year, without diminishingthe local aquifers or depending upon thevagaries of a well,” Grew said. “Besides, insome remote locations, it really is the bestand only good solution to creating a watersupply.”FOR instance, in Guanacaste, whereconstruction of hotels, condos and privatevillas are booming, and the aquifers arebeing heavily drawn upon to support thatgrowth, a viable alternative for both touristfacilities and the local population is RWH.While we in Costa Rica think ofGuanacaste as semi-arid, in fact, even alongthe coast it receives 215% more annual rainfallthan Seattle, Washington, a city mostNorth Americans consider too rainy to livein comfortably! But since most of that rainfalls seasonally and the hot sun parches thelandscape during the dry season, we tend toforget that it actually rains an abundant 75-plus inches per year.This rain represents an abundant and virtuallyuntapped resource to provide puredrinking water to both residents and touristsin Guanacaste. By designing the RWH systeminto the original plans for a home, commercialor industrial structure, the optimumsystem and economics can be achieved.Such systems can be as simple and minimalas a rain barrel to help reduce the use ofexpensive potable water on landscape irrigation(plants much prefer rainwater withoutthe chlorine and high sodium of treatedwater), or a full potable system designed tofulfill all the needs of the residents, andrequiring more storage and filtrationresources.THE most advanced systems can beincorporated into the architecture of thestructure, thereby benefiting the residentswith not only pure water, but also adding:- thermal mass, which is ideal for helpingto naturally cool the house/structure- naturally softened, mineral-free waterfor evaporative cooling systems, whichoperate without closing the house up as traditionalair-conditioning systems require- a safety system in the form of immediatelyavailable pressurized water for firesuppression.Costa Rica, like Nicaragua, is blessedwith tremendous water resources comparedto much of the world, but it must not ignoreopportunities to protect those resources,especially when doing so benefits all sectorsof society.One of the most effective means to dothis is to encourage rainwater harvesting asis done by the governments of Australia,New Zealand, Singapore and Bermuda. Allthese countries are in the tropics and allthree either encourage RWH with a combinationof educational programs, buildingcodes and financial incentives, or throughlaws which actually require all new constructionto incorporate RWH systems, as isthe case in Singapore & Bermuda.LESS affluent countries in the tropics,including India, Bangladesh, Ethiopia andUganda, are adopting RWH out of simplenecessity. RWH is a technology that is scalableand adaptable to a wide range of applicationsand environments, as is the case inCosta Rica, where climate and wealth varyso much from one community or area to thenext.For more info on RWH, e-mailRWH@cox.net or visit www.rainharvesting.com. Remember, we are all downstreamfrom someone!Jim Ryan splits his time betweenScottsdale, Ariz. and San José, Costa Ricaand became an advocate for RWH’ing afterhaving purchased land along the Pacificcoast of southern Nicaragua, where abundantrainfall and limited groundwater arethe norm.
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