Fig. 5: Schematic diagram of one BWDR.

One BWDR consists of a 4 ¼-inch (10.80 cm) ID PVC reservoir and 9 meters of looped ¾-inch (1.91 cm) ID PVC pipe, circulating a total of 7 L of bulk water. Along the pipes are removable sections as well as coupons with a PVC sample disk that fits into holes drilled along the invert of the pipe. Each BWDR has (1) a 5 L PVC reservoir, (2) an adjustable flow meter, (3) a 3D-printed valve to control the flow rate, (4) a centrifugal pump (24 V DC), and (5) ¼-inch (0.64 cm) ID black vinyl tubing connecting the reservoir to the piping. BWDRs were operated for 12 weeks to generate mature biofilm prior to their experimental period54.