Kerala Building Rules- Rainwater Harvesting

Chapter XVI-A RAINWATER HARVESTING

109A.  Rooftop Rain Water Harvesting Arrangements.-

(1) Unless otherwise stipulated specifically in a town Planning Scheme,  workable rooftop rainwater harvesting arrangements shall be provided as an integral part of all new building constructions for the following occupancies, namely:-
i) Group A1- Residential (with floor area of 100 sq.m or more and plot area of 200 sq.m or more)
ii) Group A2- Special Residential
iii) Group B- Educational;
iv) Group C- Medical/Hospital
v) Group D- Assembly
vi) Group E- Office/Business
vii) Group G1 and Group G2 Industrial (only for workshops, assembly plants, laboratories, dry cleaning plants, power plants, Gas plants refineries, diaries food processing units and any other occupancies notified by the Government from time to time) viii) Group1(1)  Hazardous (Automobile wash stall, automobile Service Stations, Service Garages with repairing facilities and any other occupancies notified by the Government from time to time);
Provided that the floor area to be considered  shall be the total floor area in all floors:
Provided further that, the rainwater harvesting arrangement is not mandatory for thatched
roofed buildings.

2)  The components of workable rooftop rainwater harvesting arrangement as stipulated
in Sub-rule (1) above, shall include:
i) Roof catchment area
ii) Roof gutters
iii) Down pipe and first flush pipe arrangement
iv) Filter unit and
v) Storage tank with provision for drawing water and spillover

3)  The minimum capacity of the storage rank  as stipulated in Sub-rule (2) (v) of the
rooftop rainwater harvesting arrangement shall be at the rate given below:
Group A1- 25 litres/Sq.m
Group A2- 25litres/sq.m
Group B- 50 litres/Sq.m
Group C- 50 litres/Sq.m
Group D- 50 litres/Sqm
Group E- 50 litres/Sq.m
Group F- Nil
Group G1 and Group G2- 50 litres/Sq.m
Group H- 25 litres/Sq.m
Group I- Nil

4)  The municipality shall enforce workable artificial ground water recharging arrangements as an integral part of all new building constructions through collection of roof top rainwater.

5)  The component of workable artificial ground water recharging arrangements as stipulated in sub rule (4) above, shall include:
i) Roof catchment area
ii) Roof gutters
iii) Down pipe
iv) Filter unit
v) Recharge well/percolation pit

6)  Wherever rooftop rainwater harvesting arrangements as stipulated in sub rules (1) to (3) above are provided, additional arrangements for carrying the spill over water from storage tank to recharge well or percolation pit need only be provided

7) The owner(s)/occupier(s) shall maintain the rooftop rainwater harvesting arrangements and artificial ground water recharge arrangements in healthy working condition

8)  The Municipality may, in exceptional cases such as water logging or impermeable subsoil conditions to considerable depths, exempt construction from the mandatory groundwater recharging arrangements.