DUX DRAIN-O-LIQUID is a highly concentrated acidic drain cleaner which contains Sulphuric Acid. Ideal for cleaning blocked drains and grease traps. It disintegrates paper, rags, sanitary products, grease, sludge, soap, fat, wood, hair, all types of food and organic matter. DUX DRAIN-O-LIQUID is recommended for external drains only. Will not harm septic tanks when used according to directions.