A washing apparatus comprises a screening apparatus having a first screening deck located below a second screening deck, wherein the first screening deck passes material that is larger than the material passed by the second screening deck. A liquid delivery system delivers liquid onto the first screening deck to wash material on the first deck. Material that passes through the first deck is conveyed upwards and delivered onto the second deck for dewatering. The apparatus is able to wash and dewater aggregate material in a single unit with a relatively small footprint and relatively high throughput.