Ключевые слова: background, bacterium, canal, canalization, dirtiness, dirty, discharge, ditch, ditches, drain, drainage, duct, environment, filthiness, filthy, flowing, industry, natural resource, natural resources, pollutant, polluted, pollution, poluted, resource, resources, sanitary, sewage, sewer, sewerage, slop, system, trash, treatment, unclean, waste, wastes, wastewater, water,