Bangalore Water Supply & Sewerage Board [Bwssb] — Rain water harvesting

Address: #54, 3rd cross, vasanta layout, Munnekolala, Marathahalli, RR No.E-237519

Sir, my sister having a tin sheet house at Marathahalli, Munnekolala. Taken bwssb water connection RR No. E-237519. BWSSB charging RWH(Rain water harvesting). Site measurements 30'X40'. Approached concerned authorities at AECH layout, kundanahalli regarding RWH charges. They r not ready to hear my complaint. If roof house, then RWH can be provided. Then how can tin sheet house can provide RWH. Please suggest me to whom I can approach to avoid RWH charges.