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Austin's drainage charge is assessed on utility bills and pays for solutions to flooding, erosion and water pollution.

Rate Increase

The City of Austin Fiscal Year 2025-26 budget includes a Drainage Charge base rate increase. The new base rate will be $0.00593 impervious cover square foot per month. That is an annual change of $8.04 for a residential customer with 3,100 square feet of impervious cover and 37% impervious cover. The new rate will be reflected on November utility bills.

Drainage Charge Calculation

The drainage charge is calculated individually for each property, based on the amount and percent of impervious cover. Less impervious cover means a lower charge.

What is impervious cover? It includes:

  • Rooftops
  • Patios
  • Driveways, paved and unpaved
  • Parking lots, paved and unpaved
  • Other surfaces that do not absorb rainfall.

Impervious cover has a significant impact on stormwater. It increases the amount and speed of stormwater. It also increases the amount of pollutants in stormwater. To find out more about how impervious cover contributes to problems such as flooding, watch the Pervious v Impervious Cover YouTube video.

What is My Impervious Cover?

Use the Find My Drainage Charge tool to see the impervious cover on your property. The Find My Drainage Charge tool works best with Internet Explorer 9 or higher, Firefox, Google Chrome or Safari.

  • Go to Find My Drainage Charge tool
  • If your information is unavailable, it may be due to a confidentiality request by the account holder. For more information, visit the Austin Energy Confidentiality & Customer Rights page.
  • Impervious cover may not be shown if the property was recently developed after the latest aerial photography was taken.

Stormwater Management Discount

If you collect rain water on your property, you may be eligible for a discount on your drainage charge. The discount is available to both residential and commercial properties. However, you must exceed development requirements to be eligible. Find out more about the Stormwater Management Discount.

Estimate Your Drainage Charge

If you are planning changes to the impervious cover at your property, you can use this calculator to estimate your drainage charge.

Learn More

Drainage Charge Calculation

This is how the drainage charge is calculated:

Monthly Drainage Charge = Impervious Cover (sq ft) X Monthly Base Rate X Adjustment Factor

Definitions:

  • Fiscal Year 2025 Monthly Base Rate: $.00565; Fiscal Year 2026 Monthly Base Rate: $.00593
    • The fiscal year starts October 1. The new rate will be reflected on November utility bills.
  • % of Impervious Cover: Impervious Cover / Property Size
  • Adjustment Factor (AF) unique to each property: (1.5425 x % Impervious cover) + 0.1933
How does the City know how much impervious cover is on each property?

The impervious cover data is generated using aerial photography collected every two years. Each pixel on the aerial photography represents 6 inches on the ground. The accuracy is suitable for defining the edges of buildings, patios, driveways, and other types of impervious cover. This data was used to create impervious cover maps seen on the Find My Drainage Charge Map Tool. (For best results, use Internet Explorer 9 or higher, Firefox, Google Chrome or Safari.) 

For properties developed or modified after the latest aerial photography, we use building permit data. Bills are typically adjusted based on the latest aerial photography in February during odd-numbered years. 

Drainage Charge for Commercial and Multi-Family Properties

The drainage charge is calculated the same way for everyone based on the amount and percent of impervious cover such as driveways, rooftops, parking lots, patios and walkways. 

Property Owners or Representatives 

For multi-family properties with five or more units and for properties with multiple businesses located on them, the City will bill the property owner or their representative for the drainage charge, whenever possible. Prior to November 2015, the City billed individual vacant or occupied units. The City bills individual residents for duplexes, triplexes and fourplexes, dividing the charge evenly among the units. 

Allocating the Charge 

Property owners may pass the drainage charge on to their residents or tenants. Whether and how they choose to allocate the charge to each unit is up to them as the bill payer for the property, keeping in mind any applicable provisions in their lease agreements as well as the requirements in City Code Chapter 15-9 (Utility Service Regulations). Property owners may download the Notice to Apartment Residents (pdf) and/or the Notice to Businesses (pdf) and provide a copy to their residents. 

Billing Concerns

Your drainage charge is based upon the amount and percent of impervious cover at your address. The impervious cover data was collected through aerial photography, LIDAR data and development records. We review and update our data on an ongoing basis as more information becomes available.

If, for any reason, you think there’s an error in your drainage charge, please fill out the Drainage Charge Inquiry and Support form or call our Customer Care Center at Austin Energy at 512-494-9400 to let us know. This is the first step to initiate a review of your account. Here are some things you may want to be aware of before you call: 

  • You can check the impervious cover at your property using the "Find My Drainage Charge" tool.
  • The City’s data on your impervious cover may not be the same as the appraisal district’s improvement values on your tax assessment. That is because the City includes driveways, walkways and other impervious areas not reported in the appraisal district data.
  • In some cases, the shaded impervious cover shown on the map does not line up with the photograph beneath it. This is due to the aerial photography being taken at an angle, but it does not affect the amount of impervious cover. This is particularly likely to occur with tall buildings.
  • The monthly charge per square foot of impervious cover is less than a penny, so small discrepancies in the amount of impervious cover may have little impact on your bill.
  • We may be able to lower your bill if you have an uncovered wood deck or an unpaved section on your driveway.
  • Frequently, there is no change to the drainage charge after a review.
  • Occasionally, the drainage charge increases after a review. This typically happens when we are reviewing impervious cover in one area of the property, but discover impervious cover in another area, sometimes covered by trees or newly built.
  • You may be asked to provide supporting documents, but often we can resolve your request through a phone call.
  • You may be asked to provide City staff access to your property to verify your information. 

Administrative Review and Hearing 

City Code section 15-2-12 and City Code Chapter 15-9 Article 12 are the relevant sections of the City Code for disputing your drainage charge. An administrative review by the Watershed Protection Department comes first. During this process, which is initiated by a customer call, City staff will review your records to verify the information that you provide. If you are not satisfied at the conclusion of this review, you may request an administrative hearing by an independent hearings officer. 

Paying Your Bill 

While your account is being reviewed, you remain responsible for paying the bills you have received. We will issue you a credit (or extra charge), if it turns out there has been an error. 

Assistance Paying Your Charge 

Residential customers may request a reduced drainage charge based on financial need through the Customer Assistance Program. This discount on the drainage charge is only available to those being billed directly by the City for drainage. It is not available to residents of multifamily dwellings for which the property owner or owner’s agent pays the drainage charge. 

Documents and Resources