Winter Quarter Average

bwa-visual-winter-quarter-average-seasonsIn December 2021, Benbrook Water Authority began tracking customer water usage for the purpose of using the Winter Quarter Average (WQA) method to approximate our customers’ wastewater usage. This was followed in May 2022 by the adoption of Resolution 2022-02, instituting a revised wastewater rate and billing structure incorporating the winter quarter average methodology, effective June 1, 2022.  

Managing your water usage in the winter months can help to minimize future sewer bills. Here's what that means for valued customers like you.

What is Winter Quarter Average?

Winter Quarter Average (WQA) is a method for water utilities to bill for customers’ wastewater usage over the course of each year which focuses on more accurately approximating indoor water usage so that customers are not billed for warm weather activities such as watering lawns or washing cars. This method is considered an industry best practice. 

Please note: The Winter Quarter Average method does not apply to your drinking water usage. The “water” line item on your bill will not be affected by the Winter Quarter Average. As always, your water bill will be based on your exact usage.

How does WQA work?

Using the Winter Quarter Average means that you will be charged the same amount each month for wastewater based on your average water usage over the three winter months. We will measure your water usage from your December to March bills, discard the highest monthly usage, and average the remaining three months. That average water consumption, reflected in cubic feet (1 cubic foot of water equals 7.5 gallons), will be used to set your new monthly sewer bill beginning on your June bill and will remain the same until next year when a new winter quarter average monthly volume is calculated.


Why the switch from how usage is currently measured?

Think of your water consumption in terms of inflow and outflow. As a customer, your meter tracks water usage as it flows into your house (inflow). That same meter does not read what flows out of your house through pipes, or what you put down the drain and flush (outflow). This outflow is called wastewater, and it shows up on your bill under the “sewer” line item.


Currently, water utilities estimate how much wastewater flows out of your house based on how much water flows into it. They estimate that these amounts — your metered water usage, or inflow, and your wastewater, or outflow — are the exact same. For example, when you turn on the faucet to take a shower, utilities estimate that the exact amount of water coming out of your shower head will go down the drain as wastewater, which then needs to be treated. 

At BWA, we recognize that some of your metered inflow goes to outdoor water use and does not leave through a drain. Especially in the summer, how often do you water your lawn, spray down the slip-and-slide, water your plants, and fill the swimming pool? 

To address this, we have historically assumed your sewer usage equaled your metered water usage, but capped your “sewer” usage at 1,500 cubic feet per billing cycle. Now, by using the Winter Quarter Average method, we will be measuring your water usage during months when it is more indicative of your normal indoor usage throughout the year, and stabilizing your monthly sewer bill in the process.

What should I expect?

Customers will notice a few changes to their wastewater bills beginning in June 2022.  These changes will include a lowered base service charge and a monthly volumetric charge based on the newly adopted wastewater rates and, for residential customers, a fixed monthly volume for billing based on winter water usage.

Fixed Charges

Historically, BWA’s base charge for wastewater service included an allowance of up to 400 cubic feet (or about 3,000 gallons) per month.  This charge was intended to cover the cost of maintaining service (whether there was any usage) as well as the cost of collecting and transporting up to 400 cubic feet of wastewater each month.  With the recently adopted rate resolution, the volumetric allowance has been eliminated and the fixed charge reduced from $18.29 to about $9.50 per month for most customers depending on meter size.  This change better distributes the cost to maintain service to all customers equally.

Volumetric Wastewater Rates

Like water rates, wastewater rates are established to recover that portion of the cost of providing wastewater service which depends on the amount (or volume) of wastewater generated by each customer.  

Billing Impacts

For residential customers, the monthly wastewater billed volume will be established each spring following a calculation of the winter quarter average monthly volume (see below for a detailed explanation). With the change to winter quarter average billing, some customers, particularly those whose water usage has been historically either relatively constant throughout the year or those whose winter usage is significantly higher than the system average may see noticeable increases in their wastewater bills.  These increases will be the result of an increase in the rate applied to the billed volume and, in the case of single-family customers with significantly higher usage, an increase in the maximum billed volume from 1,500 cubic feet to 1,750 cubic feet.

How is the rate calculated?

To ensure BWA covers the cost to provide service, the wastewater volumetric rate is calculated by dividing the total cost for the Authority’s wastewater operation attributable to volume by the total wastewater volume estimated to be billed. Historically, BWA established wastewater rates based on metered water usage throughout the year.  It was understood that for single-family residential customers, there was only so much wastewater likely to be generated in each month from a home, so the maximum volume assumed for billing purposes was 1,500 cubic feet per month (which is about 375 gallons per day). 

Establishing rates based on actual wastewater usage will necessitate wastewater rates appearing noticeably higher than before winter quarter average billing was in place.  System-wide water demands are significantly higher during spring and summer months than in winter due to outdoor water usage that is not as common during winter months.  Since BWA’s wastewater rates have until now been based on average water usage over the course of a year (higher volumes) instead of the winter quarter average (lower volumes), wastewater rates were lower than they will be with winter quarter average billing.  Put more simply, with winter quarter averaging, rates will be higher, but billed volumes will be lower.

Revenue Requirements

Wastewater rates adopted by Resolution 2022-02 provided for an increase in revenues to ensure adequate future funding of BWA’s wastewater operation.  This need is the result of several factors, including future wastewater capital improvements projects, increased costs for supplies and materials due to inflation, and a recent (nearly 15%) increase in wastewater rates associated with BWA’s wholesale wastewater agreement with the City of Fort Worth.  The rates established are consistent with the rates contemplated in the Cost of Service and Rate Design Study completed in December 2020 for BWA.


If you have other questions about how the Winter Quarter Average works or how it will affect your monthly bill, please contact Customer Service at 817-249-1250 or