Airliners are supposed to dump toilet waste over bodies of water.
By this, I'm assuming large bodies of water (e.g. ocean, Great Lakes, etc.)
I also heard of this happening over 10 years ago to a house which was on the approach to Dulles Airport in the Washington, DC area. The steaming blue ball of chemicals and ... well ... you know what, crashed through the roof of a house and landed on the floor in the master bedroom.
I guess the pilots might be confusing the switch to dump the waste with the switch for the landing gear.