It’s irresponsible; the rain gutters are for clean surface water wash off and drain freely into water courses, rivers, lakes etc untreated; they’re totally separate from the sewers even though both systems run under the roads. Organic liquids should be disposed off via the sewage system - so down a toilet or a sink - where the water should be treated before being released back into the water table.

If everyone were disposing of contaminated water in the surface drainage system we’d be in big trouble.