Unit color Filter drains method terrace surface rainfall downpipes turbidity courtyard clean silt dependency water pipes open ground roof gutters storage tank contaminants building roofs Transportation storage system microorganisms catchment area key components other materials allegianceindia watering gardens harvesting system required capacity UV-resistant pipes rechargeable water first flush device Æ Water Managements Allegiance Enterprise traditional water sources Allegiance Water Management Rooftop rainwater harvesting potable household activities Rooftop Rain Water Harvesting