While latex paint is not considered a hazardous material, it cannot be disposed of unless the cans have completely dried out. There are several methods to dry out cans of latex paint, depending on how much time you have. The National Paint and Coatings Association states that paint, most of it latex, comprises the largest volume of waste collected by hazardous waste programs throughout the country. When you cannot use up or donate leftover paint, dry it out in the can and dispose of it with your regular trash.
Leave the paint can open in a warm, dry place. If there is 1 inch or less of paint in the can, this will dry it out within a few days.
Add absorbent materials, such as sawdust or cat litter, to the paint if there is more than just a little left. Stir it periodically to hasten drying.
Pour paint from a full can into other cans or containers, a little in each, so it dries quickly.
Buy some commercial paint hardener or dryer to dry paint in a hurry. This is available at many paint and hardware stores as a highly absorbent powder. When mixed with paint as directed, it will dry even large amounts within a day or two.
Leave the lids off the dried paint cans when you put them out in the trash. If you leave them closed, the trash collectors might assume they are not dried out and will leave them behind.