Indoor Budget

Sum of
days in period



Outdoor Budget

Sum of daily reference evapotranspiration
ET Adjustment Factor
Residential landscaped area
Unit Conversion Factor

The Efficiency Explorer Tool was developed with publicly available data to offer water managers a first glance at water use compared to potential water efficiency goals. It is for educational and illustrative purposes only. The Efficiency Explorer Tool was not intended and is not able to calculate water agency budgets at a level of accuracy appropriate for establishing policy. Several areas for improvement were identified as this tool was developed and the California Data Collaborative is dedicated to working with members and stakeholders to improve the accuracy and precision of this tool.

The CaDC Efficiency Explorer is a planning and education tool for local water managers and the wider California water community. This tool is the result of a rapid first assessment of Governor Brown's Executive Order B-37-16, which calls for the development of water use efficiency goals customized to the unique conditions of each urban water agency as part of a new, permanent efficiency framework.

For version one of the Efficiency Explorer, the CaDC focused on the residential component of an agency's efficiency efficiency goal. This goal is calculated as the sum of indoor and outdoor residential water use budgets, and can vary according to unique agency conditions as well as pending policy decisions.

The parameters of these two budgets are displayed in the labeled panels above. Click each parameter for descriptions, data sources, and data quality considerations for this iteration of the CaDC Efficiency Explorer.

Since data quality is an important dimension for this rapid first assessment, data quality flags are included for each agency. These flags are explained in the Data Quality section below. For additional technical details, please see the CaDC Statewide Efficiency Explorer Methodology Documentation.

For all other questions and feedback, users are encouraged to reach out to!

There are two distinct senses in which efficiency goal calculations can deviate from ground truth: precision and accuracy.

Figure (a) Systematically Accurate, Not Precise 325 of 404 Efficiency Goal Calculations | ~80%
Figure (b) Not Systematically Accurate, Not Precise 79 of 404 Efficiency Goal Calculations | ~20%

Parameter data used to calculate efficiency goals can be imprecise. Imprecision reflects deviations around a true value. The Efficiency Explorer's graphs include gray confidence bands around each agency's calculated goal to indicate the imprecision resulting from the compounded statistical error for all parameter data sources. Analogous to the relationship between the darts and the bullseye in figure (a) above, one should expect the ground truth efficiency goal values to lie somewhere within the confidence bands (for agencies not flagged as showing evidence of systematic inaccuracy). For technical details on each component error source, please see our error model. One key result from this error analysis is the break down of the aggregate goal error by budget: indoor budgets are expected to lie within approximately 3% of their estimates, while outdoor budgets are within 40%. Takeaway: while imprecise efficiency goal calculations can be further refined, they are useful first approximations of ground truth.

As alluded to above, in certain situations parameter data used to calculate efficiency goals can be not only imprecise, but also inaccurate. Inaccuracy reflects a more systematic bias away from ground truth. Figure (b) above graphically illustrates this type of error. Non-random inaccuracies can arise from situations such as the prevalence of large rural residential parcels in certain districts, which would result in systematic overestimation of goal calculations in those districts. The prevalence of brown lawns in other districts would result in systematic underestimation of goal calculations in those districts. Roughly 20% of agency efficiency goal calculations show evidence of this more problematic source of error. The component data inaccuracies are broken down in a CaDC data quality blog post. Takeaway: efficiency goals flagged as systematically inaccurate should not be interpreted as useful approximations and have been grayed out on the map.

By setting values for GPCD and ET Adjustment Factor, users can investigate how different standards for residential water use affect their agencies over different periods of time.

  • Use the Scenario Builder panel to:
    • Set scenario parameters
      • Date Range - by clicking and dragging the slider knobs
      • GPCD and ET Adjustment Factor - by typing values in the associated forms and pressing enter
    • View results for current scenario for selected Supplier
      • Residential Efficiency Goal - the residential water use efficiency goal calculated using the selected indoor and outdoor water efficiency standards
      • Residential Use - the total water use reported by the supplier multiplied by the percentage that went to residential customers
      • Efficiency - the number of acre-feet (and percentage) over or within efficiency goal. Negative percentages represent percentage within goal
      • Data Quality - a 3-tiered flag indicating supplier-level data quality concerns
      • Time Series Graph - the historical relationship between efficiency goal and actual use. Grey bands are included around efficiency goal line to indicate confidence region
  • Use the map panel to:
    • Select suppliers
    • View geographic context
    • View the Big Picture
      • Total Residential Efficiency Goal - the sum of all residential goals not flagged as systematically inaccurate for the previous twelve months
      • Total Residential Use - the sum of all residential use of those suppliers for the previous twelve months

For best experience, please use Chrome and set your browser window to fullscreen.

Important Consideration:

While the landscapes of typical suburbs without brown lawns are captured well with the photosynthetically active remote sensing approach used, there generally exists greater data quality uncertainty for rural and wooded areas.

For additional technical details, please see the CaDC Statewide Efficiency Explorer Methodology Documentation.

For all other questions and feedback, users are encouraged to reach out to!

Scenario Builder

Residential Efficiency Goal:

Residential Use:


Data Quality:

Big Picture

Useful first approximation agencies over past 12 months
Total Residential Efficiency Goal:

Total Residential Use: