Don't dispose of a stained raincoat. Many raincoats can be cleaned free of stains effectively. Decipher what kind of stains you are dealing with before you attempt to clean them. Stains that are on the surface of the raincoat are usually easier to get out than those on the inside fabric of the coat, because they can be scrubbed off of the plastic or rubber surface. Work on removing stains as soon as they happen or as soon as you notice them, as this will increase the chance that you will be able to remove them.
Check your raincoat for washing instructions. Some raincoats can be washed in the washing machine. Always wash raincoats in cold water and turn the coat inside out. Hang dry after the cycle ends. Check for dry cleaning instructions. Some raincoats can be dry cleaned, and this is an easy way to get stains out of the lining of the coat, as it's usually made of fabric.
Pour vinegar into a bowl. Wet a wash cloth with the vinegar and scrub at the stains on the raincoat. Use vinegar for both the outside of the raincoat and the inside of the raincoat. Rinse the vinegar away by using a new damp cloth that is saturated with water. Wipe away any dirt or vinegar from both sides. According to howtocleansstuff.net, place the raincoat in a bathtub full of water with ½ cup of baking soda. The baking soda will remove any other stains that may not have been taken care of with the vinegar. Let the coat soak in the mixture for at least one hour. Rinse in the shower afterward to get rid of the baking soda residue. Hang dry.
Use a bleach and water mixture on the outside of raincoats. Never use this mixture on fabric pieces that serve as liners unless the liner is already white, as the bleach can damage the colouring. Pour one part bleach and six parts water into a bucket. Use a scrub brush or a wash cloth to attack the stains on the outside of the raincoat. Watch as the bleach dissolves tough substances such as unknown grime.
Mix hand soap or washing powder with a bucket of water. Use enough so the water is concentrated but not overly filmy. Use a toothbrush, scrubber or a wash cloth to spread the mixture over the raincoat stains. Use this concoction on both the inside and the outside of the raincoat. Fill up the bathtub with water and add ½ cup of baking soda to the water. Let the coat soak to rid of the excess dirt. Rinse after one hour.