For a blocked drain in Adelaide, stop using nearby sinks, toilets or appliances and try a plunger if the blockage is minor and accessible. Avoid mixing or repeatedly using chemical drain cleaners, as they can damage pipes and create a safety risk for anyone working on the drain. Call a licensed plumber if wastewater is backing up, several drains are affected, there is a bad smell, or the blockage keeps returning. If you suspect the problem is in the public sewer network, contact SA Water, while a private pipe blockage generally needs an appropriately licensed plumber.