Click here to read some frequently asked questions about wastewater calculations.

What is wastewater and how is the amount calculated?
Wastewater is a non-metered service, and therefore, there is no exact way of determining how much wastewater goes down drains and toilets for individual customers. Like most utilities, Colorado Springs Utilities calculates projected wastewater flows by using a consistent formula for all residential customers.

Wastewater flows are calculated using a formula involving metered fresh water and a winter period average. The calculation is designed to bill for water that runs down drains and toilets and excludes, as much as feasible, water used outdoors for watering lawns, trees and gardens, car washing, etc.

With the full deployment of Automated Meter Reading in 2010, Colorado Springs Utilities now has the capability of automatically reading water meters on a specified day. We are using this new technology to simplify the wastewater calculation method for residential customers.

By using the AMR technology, a read is taken at the beginning and end of the winter period. To calculate the winter period ADU, water meters are read no earlier than Dec. 1 and no later than the last day of February.

The winter ADU is be determined by the usage between the December and February meter read divided by the relevant number of days in the period.

During December 2011, wastewater was based on your actual water consumption.  Beginning January 1st, we have improved our wastewater methodology based on customer input. Now, your wastewater will be billed the same year-round, using the lesser of your actual water consumption for the billing period or your most recent winter wastewater ADU (average daily units). 

Here is an example:

• The water meter is read Dec.1 which is the beginning of the winter period at 38886 CF.
• The water meter is read Feb. 27 which is the near the close of the winter period at 40132 CF.
• Subtract the two: 40132 – 38886 = 1246 CF
• In this example, there are 89 days between Dec. 1 and Feb. 27 so the amount of CFs used is divided by this number.
• 1246 / 89 = 14 ADU

New to your house or apartment?
Not everyone will have a winter period ADU due to moving in to a new house or apartment.

If you move into a new home during the summer period, the winter period ADU will default to 33 or the actual usage whichever is less.

If you move into your new home during the winter period, your wastewater amount will be based on your actual usage. We require at least 30 days between the first read and last read of the winter period to calculate the winter ADU, otherwise the winter ADU will default to 33. The amount of 33 aligns with tier 1 water rates which cap at 999 units and is reflective of indoor water use. 999 divided by 30 (days in a typical billing period) equals 33.3 ADU.

If you have questions about the 33 ADU default amount, you may call the Service Center at 448-4800 to learn more.