Brush Engines are pumper units used on grass fires and are specially adapted to fire fighting in rough (wildland) terrain where access is a problem and fire hydrants are few or non-existent. Brush Rigs carry from 600-1500 gallons of water and are designed for off-road areas and brush fire fighting. Some of the brush rigs are four wheel drive and carry light water or foam (light water is water that has been thinned or treated with material which allows the liquid to deeply penetrate brush.)