you might want to check with your county/city gov. ANYTHING you pour on the ground eventually works its way into wells, drinking water etc. In some areas, improper disposal can result in fines, much less contaminated soil and or water.

A quick search on home hazardous waste indicates latex paint products should be allowed to dry out ( evaporate, this is ok because there are no volatile organics) and then put in the trash

From King County ( Seattle) waste disposal
http://www.metrokc.gov/DNRP/swd/faci...t-disposal.asp