What I do to rinse my sand is to fill about 1/4 to 1/3 of a bucket with it and add water. I tend to use the garden hose to do this, aggitating the sand with the water. Then, I stir and aggitate the sand further once the bucket is filled. Then, I tip away the water and repeat until the water becomes pretty much clear after stirring, as this usually means the waste particles have been washed out of the sand.
Usually I have pretty good results with this method, though I haven't washed huge quantities before (eg, a whole bag of play sand). Not sure how much a bag contains, but I think the most I've ever done was about 5-6KG, so I'm not sure if there are better ways to wash it when it comes to larger quantites.