Pile of poo '19 times heavier than Harbour Bridge'

Australians love their pets but no one enjoys picking up after them.

Each year, Australian pets produce a pile of poo 19 times heavier than the Sydney Harbour Bridge, which can have serious implications for the environment.

As well as the over one million tonnes of excrement generated annually, plastic bags and non-compostable cat litter fill up landfill and pollute the environment, leading to dire health consequences.

Single-use plastic break down into microplastics, which can be eaten by organisms and work their way up the food chain, Central Queensland University PhD candidate Emily Bryson told AAP.

"There is still a lot we don't know about how microplastics impact human and animal health," she said.

"The best thing to do is try to avoid using them in the first place."

But leaving pet poo where it lies can be even more damaging.

Run off from nutrient-rich animal waste leaches into the soil, damaging microscopic organisms and marine life.

The poo can also contain harmful bacteria and parasitic eggs that can spread to other animals or humans.

Eco-friendly options such as compostable poo bags are gaining in popularity but pet owners need to know how to use them, Ms Bryson said.

"Compostable plastic bags really do need to be put into compost for them to break down," she explained.

"Compostable bags left in the environment or put in landfill aren't any better than regular plastic bags as they can still break into microplastics and contribute to greenhouse gas emissions."

In the past year alone, sales in compostable cat litter and poo bags have jumped by almost a third, according to retailer Pet Circle.

In some areas, particularly South Australia, dog poo can be included in organic waste bins where it is taken to be composted at industrial facilities.

But in most parts of the country, pet owners will have to do their own composting at home.

Pet Circle head vet Teagan Lever urged pet owners to research how to compost pet poo safely.

"It involves things like rotating the mixture so that there's a consistent temperature and not to use it on anything for human consumption, such as herbs, vegetables or fruit trees," she said.

Pet owners should only use bags certified for home composting, keep a dedicated pet composting bin separate from other food scrap compost bins and keep the composting temperature above 50C to 60C to kill harmful bacteria, she added.

Dr Lever also encouraged cat owners to switch to compostable cat litter options like paper or wood shavings to cut down on the 238,000 tonnes of cat litter that ends up in landfill annually.