Part of cleaning carpet is removing all of the dirt and debris from the carpet, it's great that it's not in the carpet anymore, but where does it go? the first place it ends up is the waste tank of the carpet cleaner. unlike the clean water tank that just contains fresh water ready to be mixed with chemicals and can be emptied anywhere, the waste water tank fills up and has to be emptied in the right place. There are a few places that this water should not be dumped at:
Waste Water should not be dumped on the lawn.
It shouldn't be dumped in the storm drain either.
in fact all waste water should be sent into the public sewer or dumped at a water treatment plant.
Waste water from carpet cleaning contains more then just dirt and cleaning chemicals, it contains traces of heavy metals and other toxins that are harmful to the streams, lakes, and oceans that they will end up in if not properly dumped. so no matter who cleans your carpets, make sure the waste water makes it to the right place.