Dye Testing FAQs

As a part of your City’s sanitary sewer evaluation survey (SSES), representatives from RJN Group, Inc. may be conducting dye testing in order to confirm potential sources of stormwater entering the sanitary sewer system. Dye testing is an investigation that is performed in follow-up to other inspections such as building sewer inspections.

Dye Testing

During a building sewer inspection program, RJN field crews identify potential indoor sources of clear water (sump pumps) and potential outside sources of clear water (downspouts and area drains) that may be connected to the sanitary sewer. These sources may require dye testing to confirm whether or not these connections discharge to the sanitary sewer. Dye testing consists of entering non-toxic fluorescent dye with water into a potential source (sump pump, downspout, or area drain) and tracing the dye to confirm or disprove its connection to the sanitary sewer. RJN dye testing field crews will display photo identification. Dye tests may take up to one hour to complete. If you have been asked to have dye testing done on your property, then please schedule your appointment by emailing dyetesting@rjn.com.

Dye Flooding

During smoke testing, RJN identified areas where stormwater is leaking into the sanitary sewers. Dye flooding is a technique that is used to pinpoint those locations so they can be repaired. Dyed water testing is performed by flooding an area with non-toxic fluorescent dye to identify the location and magnitude of a defect. Inflow sources are identified by dye water flooding storm sewer sections, stream sections, ditch sections, and ponding areas that may be contributing to inflow. Plugs are used to conserve water and to isolate the specific storm sewer segment being tested. Flow measurements are taken in the downstream sanitary sewer manhole before flooding and then again at peak flood conditions to quantify the extraneous flows coming from the cross-connections. At peak flooding conditions, CCTV cameras are inserted into the sanitary sewer and are used to televise the locations where dyed water is observed flowing into the sanitary sewers. Manholes adjacent to the flooded storm sewer are also inspected for defects, such as leaky frame seals and wall joints. Residents may see green dye in the storm sewers and ditches; this will dissipate quickly and does not stain the ground.