Instructions
Use the input fields below to define your rain collection system. The graphs and data table refresh automatically as calulator inputs are changed. Mouse over the the table and input labels as well as the graph data points for additional information. Only selected USA locations have automatic population of the rainfall data via the Location input. For all other locations, manually enter the monthly rainfall amounts in provided inputs.

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Rainfall (inches)
Supplement (gallons) Apply to All
Usage (gallons) Apply to All
Total
Normal Rainfall
Adjusted Rainfall
Captured Amount
Supplemented Amount
Usage Amount
Inflow/Outflow Amount
Tank Level -
Overflow Amount
Shortage Amount
NOTE: US Gallons (3.785 litres) are used when calulating volume.
* The NCEI 30yr Normal Monthly Rainfall (1981-2010) dataset is the source of the location specific rainfall data