A water transmission tubing for controlling the flow of water under pressure comprises a tubular inner liner of generally uniform cross-sectional configuration continuous with the length of the tubing and having an anti-bacterial agent for preventing the growth of bacteria on the inside wall of the tube. The inner liner contains a dispersed slip additive that forms a low friction surface inside the tubing for preventing adherence of slime to the inside of the tubing. The slip additive can comprise a fluoroelastomer, a fluoropolymer, a silicone resinous material, or mixtures thereof. The liner can be a separate inner layer of a multi-layer dripline, a monolayer form of the dripline or the inside of a drip irrigation emitter. The invention is particularly useful in subsurface treatment of wastewater.