Multi-layer drip irrigation conduit

A water irrigation conduit for conducting the flow of water under pressure comprising:

• a multiple-wall conduit comprising at least a tubular inner wall having an inner surface in contact with water traveling in the conduit, a tubular intermediate wall bonded to and surrounding the inner wall, and a tubular outer wall exposed to the exterior of the conduit and bonded to and surrounding the intermediate wall, the tubular inner, intermediate and outer walls each extending continuously for the length of the multiple wall conduit and each being substantially continuous around the cross-section of the conduit,
• the tubular inner wall comprising a polymeric material containing a biocide dispersed throughout the inner wall so as to kill slime-forming bacteria in the water traveling in the conduit and for preventing the growth of slime on the inner surface of the tubular inner wall,
• the tubular intermediate wall comprising a polymeric material substantially devoid of said biocide and having a thickness that inhibits migration of the biocide from the inner wall through the intermediate wall,
• the tubular outer wall forming a protective and weatherable barrier around the exterior of the multiple-wall conduit.

A water transmission tubing for controlling the flow of water under pressure of comprising:

• the tubular inner layer of general uniform cross section configuration continuous with the length of the tubing and having a biocide for killing bacteria in the water,
• a tubular first intermediate layer of general uniform cross sectional configuration continuous with the length of the tubing disposed on and bonded to the outer surface of the inner layer, and having a thickness and being made of a material that inhibits the movement of biocide from the inner layer through the first intermediate layer,
• a tubular second intermediate layer with general uniform cross sectional configuration continuous with the length of the tubing disposed on and bonded to the outer surface of the first intermediate layer and being made of a first material that is opaque to electromagnetic radiation harmful to the tubing, and
• a tubular outer layer of general uniform cross section configuration continuous with the length of the tubing disposed on and bonded to the outer surface of the second intermediate layer and being made of a second material that is absorbent of electromagnetic radiation harmful to the tubing.