Shake your rug outside and then take it inside and vacuum both sides of the rug thoroughly. Move your rug outside to the driveway or where you have access to a garden hose, and make a rug shampoo solution by mixing two tsp. of mild detergent in a bucket of water.
Spot clean obvious stains with a stain remover solution. Pretest a small section first to make sure the solution doesn't damage carpet fibers or dye. Apply a small amount of the solution to the stain with a white cloth. Do not scrub the stain, this could cause the stain area to spread. Blot the area instead, and rinse the area with cold water.
Wet the rug thoroughly with a garden hose, and dip a sponge or mop in the mixed shampoo solution. Apply the soapy suds to the rug, gently wiping (not scrubbing) as you go.
Rinse the rug thoroughly. Squeeze out any excess water. Rubber window squeegees work well for this task. Squeegee until no more water will come out.
Lay the rug out flat to dry, and when it feels dry turn it over to let the other side dry thoroughly.