Yes. It is illegal for gray water to be drained on surface. The Alberta Standard of Practice sets out performance objectives, design standard, prescriptive solutions and requirements related to on-site wastewater treatment systems. Wastewater is defined as liquid and water carried wastes associated with the use of water for drinking, cooking, cleaning, washing, hygiene, sanitation or other domestic purposes and includes gray water but does not include liquid waste from industrial processes. Gray water is wastewater that does not include waste from toilets or urinals and must be effectively managed and treated in accordance with this standard.