Tap water scotochromogen is

M.gordonae often found in tap water (hence called 'the tap water scotochromogen'), is a common contaminant in clinical specimens and a rare cause of pulmonary disease. It differs from scrofulaceum in failing to hydrolyse urea, nicotinamide and pyrazinamide. Ref: Textbook of microbiology; Ananthanarayan and paniker's; 10th edition; Pg: 367