Rainwater Harvesting Potential Calculator

Message from the CEO- Lanka Rain Water Harvesting Forum

None As the cost of domestic rainwater harvesting (DRWH) system depends mainly on the size of the tank, it is important to design the tank to ensure optimum performance at tolerable cost. This mathematical stimulation model developed in collaboration with National Building Research Organization (NBRO) supported by USAID is using historical climate data and physical characteristics of the rain harvesting systems such as roof area, roof surface type, first flush volume, effective storage volume and in-house water demand. to calculate the appropriate capacity of the rain water collection tank. This model will significantly benefit householders, designers and planner in Sri Lanka to design rainwater harvesting system to achieve a reliable and cost effective potable/alternative water source.
Demand Based Calculator Yield Based Calculator Feasibility of Proposed Tank Cost Estimate for RRWHS

Demand Based Calculator

Number of Persons per Family/Beneficiaries :
Water Requirement per Person-Per Day/ L : Drinking Cooking
Sanitation Washing
Number of Dry Days :
Required Water Volume for Survival (m3) :

Yield Based Calculator

Type of Roof :
Roof Area (m2) : m2
District :
Month :
User Define Rainfall (mm) :
Harvestable Yield (m3) :

Feasibility of Proposed Tank

Monthly Water Requirement/Per Person (L) : Drinking Cooking
Number of Family Members :
District :
Type of Roof :
Roof Area (m2/ft2) : m2
Proposed Tank Capacity (L) :

Remaining Water Volume at the End of Month (L)

Demand Satisfaction Percentage (%)

Cost Estimate

General Configuration

Type of Tank :
Volume of Tank (L) :
Number of Units :
Roof Length :
Roof Hight :

Materials and Fittings

Descriptive Item List
Materials :
Fittings :
Estimated cost for RWHS (LKR) :
(The estimated cost for rainwater harvesting system is based on the retail rates at date and includes an additional 15 % from actual cost to compensate the price escalation.)