The visual appearance of treated water is acceptable to a majority of target consumers.
No visible color <15 true color units (TCU).
Turbidity <5 nephelometric turbidity units (NTU) (generally acceptable).
Iron (Fe) <0.3 mg/L.
Copper (Cu) <1 mg/L.
Notes and exceptions
Visual factors include color, cloudiness, particulates, and visible organisms and vary with untreated source water quality.
Visual factors affecting consumer preference may occur within the device as well as the water itself and include biofilms, scaling, and soap scum due to hard water, animal larvae, and staining due to high levels of Fe or Cu.