Estimate Water Savings
When evaluating the cost-effectiveness of weather-based ET controller, the first step is to estimate water savings. A simple, straight-forward approach is shown below. You must enter the data for Columns A, B, E and F. The EstimateWaterSavings.pdf file may be downloaded, printed and used as a worksheet to indicate the information that you need from other people. The EstimateWaterSavings.excel file may be download and they will automatically compute the rest of the columns and your water savings.

The chart below shows the ETo for El Dorado county in 2004 with the exception of the Dec rainfall number. That data was not available from CIMIS Camino ET weather station. So, the rainfall from the CIMIS Sacramento ET weather station was used. This approximation is sometimes necessary.