Smoke Testing Notification Letter

When smoke testing is scheduled for an area, customers and residents will receive a letter from the St. Johns County Utility Department that provides dates, locations, a description of the process, and other important information. A sample is provided below.

RE: Inflow/Infiltration (I/I) Reduction Program Sanitary Sewer Smoke Testing

Dear Resident or Property Owner:

This letter is to notify you that St. Johns County Utility Department (SJCUD) is in the process of implementing an Inflow/Infiltration (I/I) Reduction Program and is planning to start sanitary smoke testing in your community within the next thirty days. The program objective is to remove storm water sources from the sanitary sewer system, keep wastewater treatment costs and sanitary sewer rates low, and protect the environment.

Smoke Testing is a standard method of detecting sewer defects and storm water cross connections to the sanitary sewer system. Smoke testing consists of placing a high capacity blower on top of a sanitary sewer manhole and forcing “smoke” down into the sewer system. The smoke, under pressure from the blower, travels through the sewer system and escapes through any connection, cracks, leaks, etc., along the way. This quickly reveals sources of I/I within the study area. See attached Smoke Testing FAQ for commonly asked questions about the process.

The St. Johns County Utility Department will be performing the smoke testing and all personnel will have proper identification and vehicles marked. The smoke used for smoke testing is non-toxic and non-hazardous and is manufactured specifically for this purpose. It leaves no residual or stains, and has no effect on plants or animals. The smoke should not enter your building, but if it does, it will have a distinct oder and should only last a few minutes with proper ventilation.

Both the St. Johns County Fire Rescue Department and the Sheriff's Officewill be made aware of the smoke testing project areas and schedule. Reminder notices will be given to residents at least 24-48 hours prior to work in the specific area. Please note, all plumbing fixture drain traps must be filled with water prior to smoke testing. Please perform the following tasks to ensure smoke does not enter your home:

  • Make sure all drain traps and plumbing fixtures have water in them. Fill seldom used drains (such as floor drains, garage sinks, etc.) with water by running the faucet for 30 to 60 seconds or filling the drain with approximately 3 cups of water.
  • Prepare drains as soon as you receive this smoke testing notice, this only needs to be done once before testing begins.
  • You do not need to be home during the smoke testing field work.
  • Smoke should not enter your home; however, if it does this could be an indication of a defect in your plumbing system. This defect could allow sewer gases to enter inside your home, which is a potential health hazard. Corrections of such defects on private property are the responsibility of the property owner, and a licensed plumber should be consulted to ensure the proper corrections are made. If smoke does enter your home or building, please notify the field technicians who are conducting the test.

The information gathered during the smoke testing project will be used to create a prioritized plan to reduce I/I impacts to the sanitary sewer system. Sewer defects will exist on both public and private property and will need to be corrected in a timely manner. After the smoke testing is complete, notices will be sent to those property owners that will need to make corrections. Often times, it can be as simple as removing a connected roof downspout and letting it drain above ground, or replacing a broken or missing lateral cleanout cap in your yard. SJCUD will assist homeowners in determining the best approach in disconnecting I/I sources and rerouting storm drainage. Reducing I/I will keep sanitary sewer rate charges low, while also protecting the environment.

We appreciate your patience and understanding and will make every effort to minimize the inconvenience or disruptions this project may have on you. If you have any further questions or concerns regarding smoke testing, please call 904-209-2700. SJCUD is also maintaining a website designed for the I/I Reduction Program. For project updates, project maps, important notices, and more information please visit:


Gordon Smith, PE
Utility Engineering Manager






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