From bleaches, disinfectants and detergents to pest sprays and paints, many kitchen cabinets and laundry shelves are stacked with bottles and tins of household chemicals.<\/p>\n
Chemicals are ubiquitous in modern life. They are readily available from supermarkets or hardware stores, but can become environmental pollutants if incorrectly stored, used and disposed of.<\/p>\n
Prof Stuart Khan, an expert in water quality and treatment at University of Sydney, says there are \u201cthousands of different chemicals\u201d that flow down the shower, sink or toilet and end up in the sewerage system. Wastewater contains low concentrations of all sorts, he says, including herbicides and pesticides used to grow food, detergents and chlorine bleaches used in cleaning, and antibacterial agents and fragrances in personal care products.<\/p>\n
Sign up for the Breaking News Australia email<\/a><\/p>\n Anything used or disposed of outside, such as paints and oils or petroleum-based solvents, risks ending up in the storm water system. \u201cThat\u2019s a problem because storm water can run off into freshwater environments, local creeks and rivers, where if there are high concentrations of some of those chemicals you can have ecological consequences.\u201d<\/p>\n A recent study<\/a> of indoor dust and soil samples from across Victoria detected trace metals, Pfas<\/a> (per- and polyfluoroalkyl substances) compounds \u2013 commonly referred to as \u201cforever chemicals\u201d, pesticides, products of fossil fuel combustion, and pharmaceuticals (including antibiotics, antidepressants and anti-inflammatories), although most were below toxic thresholds.<\/p>\n How should you safely dispose of chemicals without risking harm to the environment?<\/p>\n Remember the three Ps \u2013 pee, poo and paper<\/p>\n \u201cEvery drain in the house \u2013 kitchen sink, shower, washing machine, as well as the toilet \u2013 feeds into the same sewerage system,\u201d says Jess Walker, Melbourne Water\u2019s head of the Western Treatment Plant and sewage transfer.<\/p>\n When chemicals \u2013 such as fats and oils, paint and solvents or harsh cleaners \u2013 are poured down drains or flushed down toilets, they can block pipes and interfere with the natural biological processes used in wastewater treatment.<\/p>\n \u201cMost people probably don\u2019t think much at all about what goes down the drain and where it goes,\u201d Khan says.<\/p>\n He says pharmaceuticals and antimicrobial agents (such as triclosan, an ingredient in a variety of antibacterial soaps and detergents) are not well removed by treatment systems, and can end up in the environment<\/a>. \u201cWe get measurable concentrations of things like paracetamol and aspirin and ibuprofen and many, many other pharmaceutical type chemicals.\u201d<\/p>\n Cooking oils, out-of-date milk or the residues of a roast dinner can contribute to the buildup of fats, oils and grease<\/a> \u2013 known as FOG \u2013 in wastewater pipes, and the growth of fatbergs.<\/p>\n When products containing Pfas<\/a> \u2013 such as stain-resistant carpets and upholstery, water-resistant clothing, food packaging and cosmetics \u2013 are used and washed, those chemicals can end up in waterways or the environment. \u201cThe main problem with Pfas is its environmental longevity,\u201d says Khan. \u201cIt\u2019s very, very slow to naturally degrade \u2013 potentially hundreds of years for some of these chemicals to degrade in the environment.\u201d<\/p>\n The level of wastewater treatment can also differ depending on where you live. \u201cIn Sydney, most of our sewage just goes straight to three big ocean outfalls, Malabar<\/a>, Bondi and North Head, with quite limited treatment along the way. So there are many chemicals that are barely removed at all.\u201d<\/p>\n Consumer choices can have an impact at scale, Khan says, like the shift towards phosphorus-free detergents, which has reduced the amount being discharged into the environment.<\/p>\n Ben Armstrong, principal manager environment at Sydney Water, says the only things that should be flushed down the toilet are the \u201cthree Ps\u201d: pee, poo and (toilet) paper.<\/p>\n In the sink or shower, it should be just soap suds and water.<\/p>\n