Get a 5 gallon bucket and fill about 1/4 with sand. Take a garden hose and spray into the sand while using your arm to swirl the sand. Works best with hot water. You can let the water just overflow but I've always preferred to just slowly dump it out to not lose too much sand.
Never do this in your sink or bathtub because the particles can clog your drains. The less you do at a time the easier and faster it will be to wash. When the water is clear after swirling the sand is clean. It's a lengthy and annoying process but don't rush it. Otherwise every time you disturb the sand it will just muck up your water.