Winter averaging sets your sewer charge from the water you use in winter. Dallas Water Utilities averages the water billed in December, January, February and March, then bills wastewater on that average or the current month’s use, whichever is less. A leak during those months raises the average and the sewer charges that follow.
The method exists because sewer flow is not metered. Dallas says on its wastewater billing page that metering wastewater is not cost effective, so it estimates it from water use. In winter, sprinklers are mostly off and most water goes down a drain. Many DFW cities use winter averaging, but the months and rules differ, so check your own utility.
A meter cannot tell a shower from a leak. A toilet that runs all winter, a dripping faucet or a hidden supply line leak all count as water billed, raising the average and every sewer charge based on it. Toilet leaks are often silent, and most come down to a worn flapper or a stuck fill valve.
Check before the averaging bills begin. The EPA’s WaterSense program suggests a few drops of food coloring in the toilet tank; color in the bowl after 10 minutes means a leak. Then read the meter, use no water for two hours, and read it again. If it moved and the toilets passed, water may be escaping between the meter and the house, and leak detection can find it.
One honest limit: fixing a leak after the averaging months does not lower that year’s average automatically. Dallas’s leak adjustment program reprices excess water from a repaired leak, but it states that the adjustment does not cover wastewater or sewer leaks. Keep the repair date and receipts, and ask your utility whether your winter average can be reviewed.