Painting - paint thinner

how do I properly dispose of paint thinner?

You'll have to contact your local authorities on that one
The town offices (waste transfer, hazmat, etc...), or local/state DEP

It can vary from having to save it till hazmat (hazardous material) day at the dump, to pouring it down the toilet (yes, it sounds crazy but in some places that's the accepted way)-but don't do that unless you are instructed to!

Mostly you can let the particles settle, and pour off and re-use the liquid
To find out the proper way to dispose of the sludge, again you'll have to contact your local authorities
In some places it can be thrown out, and some it must go to a haz-mat program

I must reiterate to not throw it in the trash or drain unless instructed to by the local authorties

The key for any proper disposal is that NO liquid be disposed of in your trash. So, you can put it in a can, and add cat litter (scoopable) until it is dried out. Then you can dispose of it. Give it a couple of days to let the fumes escape.

Also, in many towns they have a reclamation day where citizens can safetly dispose of old haz mat waste.

Good luck!

are you a painter or home owner.
if you have dirty thinner, and will need more, then let it sit for a couple of weeks and slowly pour off into another container. the crud will stay at the bottom and you will be able to reuse the rest.
this is a lot better for the earth. i see too many people washing up brushes and discarding a gallon. it can be reused many times.
ryan

I pour mine into a 5 gal pail that I've put a drain valve about 4 inches off the bottom, the crud settles out and whenever I need some I just open the valve and presto, clean thinner.