Water Bill Calculations

How to Calculate Your Bill under the Water Rates Adopted in 2017:

1. Determine your Account Type (Customer Class), Location (Inside or Outside City limits), and Service Size.
   • May be found on your most recent bill and in our Water Account Details (PDF) list sorted by Service Address.
2. Find the Bimonthly Fixed Service Charge for your Service Size in the 12/1/2017 column of that rate table (or the Fire Services table if applicable).
   • All Water Rate Tables displayed at the bottom of this page were originally included in the mailed Special Notice (PDF).
3. Estimate the Units (1,000 gallons) of water that your account uses bimonthly (in two months).
4. Calculate your Water Quantity Charge by multiplying your Units by the applicable Cost Per Unit in the 12/1/2017 column for your Customer Class and Location (Inside or Outside City).
   • For Single-Family Residential accounts:  Multiply each Tier of Units by its Cost Per Unit and sum those results to get your total Water Quantity Charge.
5. If your account is in a Pumped Zone as shown on the Elevation Surcharge Map (PDF), calculate your Elevation Surcharge by multiplying your Units by $1.84.
   • Applicability of this Surcharge may be found on your most recent bill and in our Water Account Details (PDF) list sorted by Service Address.
6. Add your Bimonthly Fixed Service Charge, Water Quantity Charge, and Elevation Surcharge (if applicable) to calculate your total Bimonthly Bill.
   • Subtract $25 if you are a single-family residential customer enrolled in the RateShare Discount Program.
   • Fire Services pay their Bimonthly Standby Charge only. They have no Water Quantity Charge or other charges.

To estimate bills for later years, use the appropriate column in the rate tables (e.g., 10/1/2021) instead of 12/1/2017.

NOTE: The City of Napa bills water customers bimonthly (every two months). To estimate your monthly water costs to compare with other utilities, simply divide your total Bimonthly Bill in half.