Wastewater surcharges are charged to businesses that discharge wastewater exceeding “normal” wastewater standards. Business wastewater can be more heavily concentrated with solids and organic matter than residential wastewater, making it more expensive to treat.

Surcharge Fee Overview

All customers subject to a surcharge are notified by letter, and the monthly surcharge fees are applied to the customer's monthly utility bill. They are based on quantity and quality. Quantity is based on the lower of:

  • The actual amount of discharged wastewater
  • For customers without separately metered irrigation systems, the average winter discharge


Quality is based on the amount of solids and organic matter in your wastewater. Much of the cost of treating wastewater is in solids removal and the amount of oxygen required to stabilize and digest organic matter. The surcharge is applied if average discharge quality exceeds one or more “normal strength” quality standards established for typical residential wastewater.  It is based on site-specific sample results for Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD) and Total Suspended Solids (SS) collected for periodic sample analysis. For customers whose site-specific samples have not been or cannot be collected, surcharges are assessed based on quality standards determined for similar businesses based on Standard Industrial Classification (SIC) Codes. 

Normal Values (in milligrams per liter)

SS                     200
BOD                    200
COD                    450 


Surcharge Formula

Using an average of all applicable sample results, a surcharge will be determined for every permitted source of industrial waste based on the following formula:

S = V x 8.34 [A (BOD-200) + B (SS-200)]

Or, if the Chemical Oxygen Demand (COD) is more than 2.25 times greater than the BOD, then the formula is:

S = V x 8.34 [C (COD-450) + B (SS-200)]


S = Surcharge in dollars that will appear on the customer's monthly bills.
V = Wastewater billed in millions of gallons during the billing period.
8.34 = Pounds per gallon of water
A = Unit charge in dollars per pound of BOD in excess of 200 mg/L, currently $0.6622 per lb. If measured BOD is less than 200, the rate does not apply.
BOD = Biochemical Oxygen Demand in milligrams per liter (mg/l).
200 = Normal BOD and normal SS in mg/l.
B = Unit charge in dollars per pound of SS in excess of 200 mg/L, currently $0.4394 per lb. If measure SS is less than 200, the rate does not apply.
SS = Total Suspended Solids in milligrams per liter (mg/l).



= Unit charge in dollars per pound of COD in excess of 450 mg/L, currently $0.2943 per lb. If the COD is less than 450 mg/L, the rate does not apply.
COD = Chemical Oxygen Demand in milligrams per liter (mg/l)
450 = Normal COD in milligrams per liter (mg/l).

The surcharge billed (S) changes according to the wastewater billed (V), which may vary from one month to the next. For that reason, it is often more useful to discuss surcharges in terms of the Surcharge Factor (SF), the quality component of the surcharge formula. This is expressed as:

SF = 8.34 [A (BOD-200) + B (SS-200)]

Or, if the COD is more than 2.25 times greater than the BOD, then the formula is:

SF = 8.34 [C (COD-450) + B (SS-200)]

For additional information, refer to sample surcharge calculations or utilize the Surcharge Calculator.

Request Surcharge Resampling

Commercial customers who currently pay a wastewater surcharge may request that their business be resampled and their surcharge reassessed. Customers must make resampling requests via the Surcharge Resampling Request Form interface link icon or in writing to:

Austin Water's Pretreatment Program
3907 S. Industrial Drive, Suite 100
Austin, TX 78744

Should Austin Water grant the request, resampling will consist of two (2) sample collections on two (2) separate, but consecutive, days. The newly calculated surcharge will be used for future utility bills only. No credits or debits would be applied retroactively.

Depending on if there has been a major change in the pretreatment device(s) or the elimination of a waste-producing device, the following requirements would apply:

If no major changes have occurred:

  • The customer will be responsible for resampling and analysis costs as described in the current City of Austin Approved Fee Schedule.
  • Payment must be received before resampling, which shall be scheduled within 30 working days after payment receipt. Austin Water may deny the resampling request, or delay resampling (with notification to the customer), if resources to meet customer demands are limited.
  • New resampling results, plus historical data from up to three (3) previous calendar years, will be averaged to calculate the new surcharge.
  • Customers may gain approval for only one (1) resampling per calendar year.

If the customer documents a major change in pretreatment devices or the elimination of a waste-producing device:

  • The resampling will be performed at no additional cost to the customer.
  • The new surcharge calculated would be based on the new re-sampling results only.
Tips to Reduce Your Surcharge

You can do the following to help reduce surcharges, curb pollution and prevent costly plumbing problems:

  • Keep waste cooking oil out of drains.  Before washing, wipe oily pans thoroughly with a used paper napkin and/or collect and sell it to rendering facilities.
  • Scrape food from plates into a trash bin. Food waste, whether chopped, un-chopped or pureed, does not belong in the drain. Moreover, garbage disposal/grinders are prohibited for commercial food establishments.
  • Install and maintain screens over all sink and floor drains.
  • Conserve water, including implementing these water saving tips.
  • Follow an appropriate grease trap pump-out schedule to keep it functioning properly. Many traps will have to be cleaned more often than the once every three (3) months minimum.  For more information:
  • Do not use prohibited enzymes, bacteria or other agents at your facility.

Any improvements will not be reflected in your surcharge bills until the next time your wastewater is resampled and your surcharge is reassessed. However, if you have taken any steps to improve your wastewater quality, you can request surcharge resampling.

Other Helpul Information and Resources: