Wastewater Averaging

Your water meter measures how much water you use each month, but there is no meter on your wastewater line. Austin Water uses a wastewater averaging method to estimate how much wastewater your household or business sends into the sewer system each year and sets your monthly wastewater charge accordingly.

Your wastewater average is calculated once a year during a three-month period in the fall and winter, when most customers naturally use less water outdoors. Because outdoor water uses like irrigation, filling pools, or washing cars doesn't go into the sewer, averaging taking place during winter months gives you the most accurate and typically lowest wastewater rate for the year ahead. Once set, your wastewater charge is fixed for the next 12 months regardless of how much water you use.

This helpful video explains wastewater averaging, how we calculate it and what you can do to make sure you receive the best fixed monthly wastewater rate possible.

Use the Wastewater Averaging Calculator to estimate your rate.

Your Wastewater Averaging Period

Austin Water reads more than 250,000 meters across 20 billing cycles. Your billing cycle number determines when your meter is read and when your three-month averaging period begins and ends. You can find your billing cycle number in the top left of your water bill.

Your actual read dates may vary slightly from the dates listed due to scheduling changes such as weather conditions.

2025–2026 Wastewater Averaging Period

How to Lower Your Wastewater Rate

The best way to lower your wastewater charge is to conserve water during your three-month averaging period. Cutting back on outdoor water uses like irrigation, car washing and pool filling reduces the total water use used to calculate your average, which lowers your fixed monthly wastewater charge for the following year.

Residential Customers

To qualify for wastewater averaging, your account must be active for at least 60 consecutive days with a minimum of 100 gallons billed per billing period during the averaging window.

Zero Usage During the Averaging Period

• If one of your three averaging months shows zero usage, that month is excluded and your average is calculated from the remaining two months.
• If two or more months show zero usage, you will receive a default wastewater average of 5,000 gallons per month.

Why Wastewater Costs More Than Water

Wastewater is more expensive to treat than drinking water. It contains food scraps, detergent, human waste, toilet paper and other materials that require extensive treatment before the water can be safely returned to Austin's rivers, creeks and streams. Learn more about our service rates and fees.

Non-Residential Customers

For new non-residential accounts, the wastewater average is determined using one of the following methods:

• The previous customer's wastewater average for that account
• Actual water usage (gallon for gallon), where wastewater charges equal the same volume as measured water use until an averaging period is completed

Zero Usage During the Averaging Period

If one of your three averaging months shows zero usage, that month is excluded and your average is calculated from the remaining two months.

• If two or more months show zero usage, your wastewater charges will be based on actual water usage until a new average can be calculated in the next averaging period.

Non-residential customers with irrigation meters are billed for wastewater at the same volume as their domestic water use.

For commercial default rates, see the Austin Water service rates and fees schedule.