2025 Orange County Water Demand Projection Model
Customers billed at bimonthly intervals are divided into two groups, and each group is billed every second month. Bimonthly meter readings contain water use that occurs over a span of three calendar months. For example, April use equals the fraction of April consumption billed in April and June (billing group 1) plus the fraction of April consumption billed in May (billing group 2), per Equation 2-2 .
𝐴𝑝𝑟𝑖𝑙 𝑈𝑠𝑒 = ൭ቀ ଵ ସ
𝐵𝑖𝑙𝑙𝑒𝑑 𝐴𝑝𝑟𝑖𝑙 𝐶𝑜𝑛𝑠𝑢𝑚𝑝𝑡𝑖𝑜𝑛 + ଵ ସ
𝐵𝑖𝑙𝑙𝑒𝑑 𝐽𝑢𝑛𝑒 𝐶𝑜𝑛𝑠𝑢𝑚𝑝𝑡𝑖𝑜𝑛ቁ ×
భ మ ௨௧௦ା
భ మ ௨ ௨௧௦
ଵ ଶ 𝐵𝑖𝑙𝑙𝑒𝑑 𝑀𝑎𝑦 𝐶𝑜𝑛𝑠𝑢𝑚𝑝𝑡𝑖𝑜𝑛 ×
൱+ቆ
భ మ ௨௧௦ାெ௬ ௨௧௦
భ మ ௨ ௨௧௦
ெ௬ ௨௧௦
Equation 2-2
ቇ
భ మ ௨௧௦ାெ௬ ௨௧௦ା
భ మ ௨ ௨௧௦
Figure 2-3 depicts smoothed water use for an agency whose billing structure changes from bimonthly to monthly in late 2022.
5000
Bimonthly
Monthly
Billed Water Use
4000
3000
2000
Smoothed Monthly Water Use
1000
0
Figure 2-3: Example smoothing of consumption for an Agency with a Billing Structure that Changes Over Time If an agency employs both monthly and bimonthly billing cycles for billing sectors that fall into a single model demand sector, a weighting of smoothed monthly (m) and bimonthly (b) water use (q) is employed to average use (q M,avg ) over the two cycles ( Equation 2-3 ).
𝑞 ெ,௩ =𝑤 ×𝑞 +𝑤 ×𝑞
Equation 2-3
The weighting factors are defined in Equations 2-4 and 2-5 .
ಾ, ା ಾశభ, ൫ ಾ ାଶ ಾశభ,್ ା ಾశమ,್ ൯ା൫ ಾ, ା ಾశభ, ൯
𝑤 =
Equation 2-4
ಾ,್ ାଶ ಾశభ,್ ା ಾశమ,್ ൫ ಾ ାଶ ಾశభ,್ ା ಾశమ,್ ൯ା൫ ಾ, ା ಾశభ, ൯
𝑤 =
Equation 2-5
2.1.3
Development of Retail Agency Driver Units
Driver units reflect the scale of a water use sector indicative of the number of water users. Total water consumption (Q) is derived by multiplying the number of driver units (N) by the rate of water use per driver unit (q), as shown in Equation 2-6 .
2-5
Appendix G - 24
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