Abstract: An improved water nozzle (100, 200) for use in a horizontal drill string (14) to prevent clogging of the string when water flow is stopped so a new section of drill rod (12) can be added to the string. The nozzle includes a tapered passage (116, 216) in which a ball (20) is installed. The resulting ball valve allows water injected into the one end of the rod string to flow through the nozzle during drilling. However, when water flow stops for attachment of a new section of rod to the string, the valve blocks the flow path back through the nozzle so sand, gravel, and other particles are not sucked into the string causing it to clog and necessitating that the string be withdrawn from the hole and disassembled so the nozzle can be cleaned out and unclogged.