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Applications > Urban Water R-GPCD

Residential gallons-per-capita-day (R-GPCD) is calculated using the formula below from monthly Monitoring Reports submitted by urban water suppliers as required under emergency regulation.

Monthly Water Production * Percentage Residential Use
(Population) * (Days in Month)

R-GPCD figures are compared with the 2013 baseline year's usage for the same period, the monthly average for the supplier's hydrological region, and the statewide average.  Only suppliers with a calculated R-GPCD between 25 and 1000 are used in calculation of averages.  For questions on this application, please contact the DRINC Portal Administrator.

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CA Hydroregions

Urban water suppliers are required to report by the 15th of each month the previous month's water usage.  To view urban water supplier usage by Supplier, Hydrological Region, and State, select from the drop-down list below.


These charts are generated dynamically from the production data set. To download a spreadsheet of the data, please click HERE. A "0" on the bottom chart indicates that a report has not been submitted for that month. The charts may not display properly using the Chrome browser.

It is not appropriate to use R-GPCD water use data for comparisons across water suppliers unless all relevant factors are accounted for. Factors that can affect per capita water usage include:
  • Rainfall, temperature and evaporation rates – Precipitation and temperature varies widely across the state. Areas with high temperature and low rainfall need to use more water to maintain outdoor landscaping. Even within the same hydrological region or the same water supply district, these factors can vary considerably having a significant effect on the amount of water needed to maintain landscapes.
  • Population growth – As communities grow, new residential dwellings are constructed with more efficient plumbing fixtures, which cause interior water use to decline per person as compared to water use in older communities. Population growth also increases overall demand.
  • Population density – highly urbanized areas with high population densities use less water per person than do more rural or suburban areas since high density dwellings tend to have shared outdoor spaces and there is less landscaped area per person that needs to be irrigated.
  • Socio-economic measures such as lot size and income – Areas with higher incomes generally use more water than areas with lower incomes. Larger landscaped residential lots that require more water are often associated with more affluent communities. Additionally, higher income households may be less sensitive to the cost of water, since it represents a smaller portion of household income.
  • Water prices – Water prices can influence demand by providing a monetary incentive for customers to conserve water. Rate structures have been established in many districts for water conservation, but the effectiveness of these rate structures to deter excessive use and customer sensitivity to water prices vary.