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Dye testing (eg. rhodamine, fluorescein) has long been an accepted and successful method in detecting failing septic systems.

Placing an Optical Brightener sampling device into a stream

This is usually done by placing dye into a toilet bowl, flushing several times, and then visually inspecting the area around the septic adsorption field for surface outbreak. The surface of the ground immediately above the septic system as well as the surface of the ground (and receiving waters) that are immediately down gradient from that septic system are visually monitored for several days. If surface outbreak does occur (when that dye is visually detected) then that septic system is in regulatory failure. (Knowles, personal communication)

Optical Brighteners are fluorescent white dyes that are added to almost all laundry soaps and detergents because clothing made from cotton fabrics naturally looks yellowish and drab. This occurs because cotton absorbs blue rays that are present in sunlight. When Optical Brightener is applied to cotton fabrics, they will absorb ultraviolet rays in sunlight and release them as blue rays. These blue rays will then interact with the yellowish color and give the garment the appearance of being “whiter than white”. Because the main commercial use of these dyes is in laundry detergents and textile finishing, Optical Brightener dyes are generally found in domestic waste waters that have a component of laundry effluent. Optical Brighteners can therefore enter the subsurface environment as a result of ineffective sewage treatment (Fay, Spong, and Alexander, 1995) .

Optical Brighteners are removed from underground waters by adsorption onto soil and organic materials, they are removed from surface waters by adsorption and by photo decay. Since adsorption is a critically important process in the performance of septic field systems, the recovery of Optical Brighteners in nearby waters (either surface or ground water) indicates ineffective natural cleansing of waste waters (Aley, 1991).

Fluorescent dyes (such as Optical Brightener) have been used extensively for tracing surface water and groundwater because of their low detection limits, ease and economy of detection, availability and safety. Fluorescent dyes have successfully been used for delineating otherwise unpredictable groundwater movement (Quinlan, 1981). Fluorescent dyes have also been used as adsorbing tracers in order to predict the possible breakthrough of pesticides in agricultural settings (Everts and Kanwar, 1994).

Because Optical Brighteners are fluorescent white dyes that absorb ultraviolet “U.V.” light and fluoresce in the blue region of the visible spectrum, they can therefore be detected by use of a long wave fluorescent “U. V.” or a “black” light.

Two Massachusetts groups, the Ipswich Coastal Pollution Control Committee and the Gloucester Shellfish Department / Shellfish Advisory Commission, have found that Optical Brightener testing when done in combination with a larger sampling program is a reliable indicator in helping to identify: faulty septic systems, sewage exfiltration, storm drain cross-connections, and human/animal waste differentiation.

This project links together key individuals of these two North Shore groups for the expressed purpose of producing an Optical Brightener Handbook that can then be used by other water quality monitoring groups.

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