Maybe if you were to pass out from the overdose and slide down far enough to drown? Quetiapine is safe as in it won't kill you but the OD will knock you on your ass for a while (I've done it). You'd need a large bathtub to be able to slide down far enough I'd think, unless you're really small. Even then, I'm not well-versed in drowning so I'm not sure. It doesn't sound reliable.