AC Coil Cleaning Study

Project Summary

In 2014, COD staff found that wash water discharges from air conditioning unit cleaning operations were entering the city's storm sewer system. HVAC companies clean the metal condenser coils and fins of air conditioning units for maintenance and efficiency purposes. Companies are required to contain, collect and properly dispose of wash water from these cleaning activities into the sanitary sewer system.

The purpose of this study was to evaluate this wash water and to measure pollutants that reached the storm sewer system from these AC cleaning activities. We found that AC coil cleaning wash water contains increased levels of dissolved metals and suspended solids, both of which are water pollutants. 

Project Manager

Jonathan Baker

Phone: 919-560-4326 ext. 30211


AC Coil Cleaning Report (PDF)


  • Project development and review, March - May 2014.
  • Sample collection and data analysis, June 2014.
  • Final study report, September 2016.
A large HVAC unit is cleaned with a tarp underneath to collect the wastewater samples.