Unit India people colour Filter drains storage surface terrace Gutters reliance rainfall flat RCC Rooftops courtyard downpipes wire mesh turbidity atmosphere clean silt individuals stone roofs Best Method dry seasons environment crucial role drain mouths sloping roofs contamination microorganisms Transportation other deposits catchment area initial shower key components catchment roof floating debris watering gardens various Purposes harvesting system rechargeable water first flush device unpaved/open ground rainwater collection Allegiance Enterprise potential contaminants UV-resistant water pipes straightforward technique conventional water sources Allegiance Water Management rooftop rainwater structures Rooftop rainwater harvesting potable household activities Rooftop Rain Water harvesting