There's absolutely no problem with disposing of a small amount of waste from carpet cleaning into the sewage system.
I can't remember where I saw it posted, but another cleaner had already encountered this issue. The official told him that up to a certain amount there is no problem, it's only when the waste is above a certain volume in a day that disposal facilities have to be used.
Tell him to go and follow a wheelie bin cleaner around, they do it in the road and let the water run down the street!
I'm sure if a lot of truckmounters were honest they'd tell you they just flop the waste hose out of the van and let it run down the gutter too.
I can't remember the last time I put waste water down a customer's loo, I either use an outside gulley, manhole, or heaven forbid chuck it under a hedge or something. Since I've been detergent-free I have no problem with this morally, as the cleaning agent is biodegradable and non-harmful to the environment
