A liquid delivery apparatus includes a base assembly; a vessel into which liquid may be introduced to at least partially fill the vessel and to pressurize the liquid in the vessel; a nozzle including a discharge tube and a nozzle outlet, wherein the nozzle is rotatable with respect to the base assembly, and the nozzle outlet is provided at a distal end of the nozzle via which the liquid may be discharged from the vessel under the pressure of the liquid in the vessel; and a valve between the vessel and the nozzle to control passage of liquid from the vessel to the nozzle outlet; wherein the valve and nozzle discharge tube are substantially in line. A drive system is also disclosed that drives rotation of the nozzle with respect to the base assembly. The drive system may be configured to propel the liquid delivery apparatus along the ground.