i wash them in a pail... i fill the sand to around 2/3 of the pail, den add water to the top, stir them till almost everything comes out, den i pour away the water, and fill it again... around 4 times will do.... haha.. cos i juz washed mine this way...
if wanna save water, maybe can bring your sand to the public toilet, den wash it there? water will be free..?