Dye Testing for Septic Systems

Clermont County Public Health uses non-toxic, liquid powder tracing dye to determine where the wastewater from a home is going. The dye travels through the system and shows up a bright fluorescent green if it is discharged to a stream, ditch or surface of the ground. Dye testing can also verify if household appliances and laundry facilities are connected to the system and can confirm if two homes are connected to a single system. Dye testing is not always conducted to prove that a system is failing; it is often used to prove that a system is not failing, so the system in question can be eliminated as one of the sources of sewage on the surface of the ground. Dye testing is really about gathering information.

The process for conducting a dye test depends on what information the staff is trying to gather. If they are testing for sewage on the surface of the ground and there is a riser allowing access to the septic tank, then the dye can be placed directly into the septic tank and water added to the tank from a garden hose. Without risers on the tank, our staff will need to have access to the home and once inside will put the dye into a toilet or down another easily accessible drain. Verifying a household appliance, sump pump or drain (including a laundry tray), may require directly introducing the dye into that device. Once the dye has been poured into the system or drain, water must be run for 10 to 15 minutes to push the dye through the system. In some cases, such as a tank with a straight pipe, the dye shows up very quickly and in others, the inspector will have to come back the next day to check for evidence of dye at the suspected discharge point.