Keeping your home organized and efficient is a constant battle. Things have a way of accumulating, unnoticed, until a lot of storage space has disappeared. Old paint is a common culprit: Tackle a few painting projects and before you know it, half-empty cans will overrun your basement or garage.

I recently decided to reclaim the area occupied by paint cans in my basement, but the project wasn’t as simple as I had hoped. It’s against the law to throw away liquid paint (not that I would do so — discarded paint can pollute the environment). After doing some research and talking about my dilemma with a local painting contractor, I came up with a course of action for dealing with paint leftovers:

1. Decide if the paint is still good.
If stored properly, solvent-base paints (oil-base or alkyd) have 15-year shelf life. If you can stir the paint, it’s probably OK to use. You may have to peel off the skin at the top and filter the rest into a new container, but it’s worth the effort: The ingredients are too valuable to waste.

Latex paint has a 10-year shelf life — or shorter if it has been subjected to freezing temperatures. You can test old latex paint by stirring it and brushing it onto sheets of newspaper or cardboard. If there are lumps, the paint is no longer good and should be disposed of safely.

2. Decide what to keep.
It makes sense to store paint that you may use to touch up walls or trim. Carefully seal any loose lids by tapping around the rim with a hammer. If only a small amount is left in a can, pour it into a smaller container to save storage space, and label the contents with the color name and number, the room in which it was applied and the date it was purchased. Consolidate cans of the same color (or even slightly different tints of flat white — you can always use it for ceiling paint or primer) in a single container.

3. Find ways to use leftovers.
Even if you don’t like the color, you can still find a way to use leftover paint. The contractor I spoke with mixes leftovers of the same paint type (acrylic with acrylic, oil with oil, etc.) and uses it as primer. This is particularly effective if you are changing the wall color from a light shade to a darker one or vice versa. Mix leftovers to a tone that matches the tone (not necessarily the color — the mixture may be gray) of the final coat; apply it as an undercoat and you will have fewer problems with show-through.

Some light-color leftovers can be tinted to a more desirable color. Just bring the can to the paint store where you purchased it and ask the clerk to add pigments to achieve the color you want. (Keep in mind that the store will probably not be able to exactly match the new color should you need more of it in the future.)

4. Donate paint that you won’t use.
If you have a substantial amount of unwanted paint, offer it to family, friends and neighbors. It that fails, call a local painting contractor — many are happy to take free paint. Some churches and charities may need paint, too, especially those that help needy people with home renovations. However, some organizations, such as Habitat for Humanity, have a policy that precludes accepting hazardous materials, including paint.

5. Safely dispose of the rest.
How you dispose of paint depends upon its type. Here are some guidelines for different types of paint:

Latex and acrylic: Many municipalities encourage homeowners to solidify these paints and discard them with household trash. One method is to mix the paint with a clay-base cat litter at a ratio of two parts litter to one part paint. Do this in a place that's well-ventilated and off-limits to kids and pets. Another method is to use a paint-solidifier product. I tried Xsorb's Rock Solid and found that about a cupful solidified a quarter-gallon of old latex paint in an hour. (See Photo 1) For small amounts of paint (less than one-fourth of a can), you can mix the hardener and paint in the original container (See Photo 2). For larger amounts, it may be necessary to make a container by placing a trash bag over a sturdy box (See Photo 3).

Oil-base and alkyd: Check whether there is a scheduled hazardous-waste-collection day in your community (See Photo 4). Schedules are typically posted on a state's department of environmental conservation Web site. You may also call your city hall. Bring the paint to the specified collection site along with other toxic products you want to dispose of, such as paint removers, used solvents, pesticides and herbicides. If your community does not offer this service, call your county extension home-economics agent, the local waste-management agency, your area's water-treatment plant or the local landfill and ask what the procedure is for where you live.

Whatever type of paint you need to dispose of, it's crucial that you do it in a way that won't pollute drinking water or waterways. One gallon of paint can contaminate many thousands of gallons of water, harm fish and plant life and eventually poison the food chain.


Dos and Don'ts of Paint Disposal

Do wipe paint off of brushes and roller covers after you're finished using them. You will be surprised at how much paint you can wipe from a paintbrush and how much easier cleaning it becomes.

Do use the smallest amount of water or solvent possible to clean brushes and rollers. Recycle the water or solvent you've used by allowing the sediment to settle, pouring off the liquid for reuse and allowing the sediment to harden.

Do dispose of solidified waste according to the recommendation of your local waste-management agency.

Do remove the lids from paint cans that contain solidified latex paint so sanitation workers can see that the paint no longer poses a danger.

Don't clean brushes or roller covers unnecessarily. Wrap the tool with plastic or aluminum foil so it will stay wet until you have finished working — this works for several days or even longer if you place the wrapped tool in the freezer.

Don't pour paint of any type into drains, sewers or waterways.

Don't put paint that has not been solidified in the trash; it can leak and contaminate waterways.