When it comes to evaporating photographic liquids, always consider, that water is not the only thing evaporating. Depending on composition of your liquid you may create fumes of Ammonia, Hydrogen Sulfide, Quinone, Acetic Acid, ... these will likely not cause environmental harm at the amounts you state, but I wouldn't want to do this in my home either. While people near you may not be avid analog photographers, they still have left over paint cans, organic solvents for brush cleaning, motor oil, car batteries, expired medication, ... and none of the above in multiple gallon amounts. There has to be a way to dispose of this stuff in a legal and environmentally acceptable fashion near you.