Aims: Measure adherence and biofilm formation by cells of Mycobacterium avium, Mycobacterium intracellulare and Mycobacterium abscessus on common household plumbing materials namely stainless steel, glass, zinc-galvanized steel, copper and polyvinyl chloride (PVC). Methods and Results: Coupons in a CDC biofilm reactor were exposed to cell suspensions containing 10(5) NTM colony forming units (CFU) per ml and adherence measured for 6h. Biofilm formation (increased numbers of adherent CFU) was measured weekly to 21days in the absence of substantial numbers of suspended mycobacterial cells. Adherence was rapid and substantial with 2000-15000CFUcm(-2) adhering within 1-6h at room temperature. Biofilm numbers reached as high as 10(7)CFUcm(-2). Biofilm-grown cells of Myco.avium were more adherent compared with suspension-grown cells. Conclusions: Mycobacterium avium, Myco.intracellulare and Myco.abscessus readily adhered and formed biofilms on all types of plumbing materials. Factors influencing adherence and biofilm formation were species, plumbing material and prior growth.