Smoke Testing and the Sanitary Sewer
Inflow/Infiltration Reduction Program


Smoke Testing of Sanitary Sewer Systems – Beginning in April 2018, St. Johns County Utilities will perform sanitary sewer smoke testing. For more information, please see the Community Notice and the smoke testing map for locations: Smoke Testing Map and Details

Program Goals

Remove storm water sources from the sanitary sewer system, keep wastewater treatment costs and sanitary sewer rates low, and protect the environment. 

Smoke Testing

St. Johns County Utility Department’s Inflow/Infiltration (I/I) Reduction Program operates sanitary smoke testing and flow testing to detect sewer defects and storm water cross connections to the sanitary sewer system.  Smoke is blown into the sewer system, which then travels through the sewer system and escapes through any connection, cracks, leaks, etc., identifying points of inflow or infiltration.

Smoke Testing – Need to Know

  • Smoke testing personnel have proper identification and marked vehicles. 
  • Smoke is non-toxic and non-hazardous and is manufactured specifically for this purpose.  It leaves no residue or stains, and has no effect on plants or animals. 
  • Notices and reminders will be given to residents at least 24 to 48 hours prior to beginning work in their specific area. 
  • Plumbing fixture drain traps must be filled with water prior to testing, by running the faucet for 30 seconds.
  • Smoke should not enter your building, but if it does, it will only last a few minutes with proper ventilation. Please notify the field technicians who are conducting the test. Smoke entering your home could be an indication of a defect in your plumbing system. Corrections of such defects on private property are the responsibility of the property owner, and a licensed plumber should be consulted.

Smoke testing is used to identify sanitary sewer defects and identify corrections to reduce impacts to the sanitary sewer system. Sewer defects on private property will result in notices being sent to those property owners for corrections. 

Inflow and Infiltration

Inflow and Infiltration are extraneous clean water which does not require treatment, but flows into the sanitary sewer system, unavoidably getting treated at the Waste Water Treatment Plant, consuming capacity and increasing treatment costs. 

  • Inflow is rain water that enters the sewer system from roof leaders, floor drains, sump pumps, manhole covers, or improper connections between drainage and sanitary sewer systems.
  • Infiltration is groundwater that enters the sewer system through leaks in pipelines and/or manholes.

Inflow and Infiltration






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