consumption 6 minimal maintenance 9 professional installation cgwa regulations 8 remove contaminants replenish aquifers 4 percolation pits open spaces enhances sustainability 2 municipal supply groundwater recharge storing rainwater collecting filtering rainwater safe cost depends drinking answer industrial commercial rainwater harvesting rainwater harvesting cost government approval required rainwater harvesting answer rainwater harvesting systems rainwater harvesting answered commercial buildings answer commercial buildings benefit advanced filtration systems uv sterilization chlorination water conservation suitable