There are a few cities that claim to have Australia's best tap water — Hobart and Melbourne among them.

Key points: The taste of tap water is influenced by everything from rocks to livestock, sediment to who's drinking it.

The taste of tap water is influenced by everything from rocks to livestock, sediment to who's drinking it. Adelaide and Perth have the saltiest water in the country.

Adelaide and Perth have the saltiest water in the country. Hobart and Melbourne are in competition for the best tasting tap water.

If you've ever travelled to either and remarked on the tap water, you'd likely be familiar with the resulting bragging from locals about how wonderful their local drop is.

ABC Hobart ran a poll on social media which garnered more than 1,400 votes, with 77 per cent of people voting Tasmania's water tasted the best.

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But are Tasmanians right to be so boastful? The ABC spoke with two academics and a senior manager at the state's water authority to find out what affects the way tap water tastes, how it differs across the country and if Tasmania's water superiority complex has any basis.

What gives tap water its taste?

Taswater system performance and productivity manager Lance Stapleton said while pure rain water had no taste at all, most tap water was sourced from various different catchments which could influence the flavour.

"Sediments can impart a taste to the water, like iron or manganese in dams and lakes," Mr Stapleton said.

Iron sediments can give water a metallic taste, while algae that grows on rocks in waterways can make it taste swampy.

Different types of rocks at water sites can also affect the flavour, either purifying it or reacting with water.

If the rocks are reactive, they can infuse the water with various naturally-occurring chemicals, though these generally change the appearance of the water rather than the taste.

The water on kunanyi/Mount Wellington is some of Tasmania's cleanest. ( Supplied: Moe Khodajo )

Leon Barmuta, a freshwater ecologist at the University of Tasmania, said water in Australia was naturally on the saltier side, making that the major issue water companies must tackle in the treatment process.

"Most of Australia's surface fresh water is dominated by sodium and chloride ions because a lot of our rain comes off the ocean, so a lot of wind-blown salt comes into our catchments," Associate Professor Barmuta said.

It also comes down to who's drinking it, as some people are a lot more sensitive to changes in chemical balances than others.

"People vary quite a lot in what the concentration has to be for them to pick up a change in flavour," Associate Professor Barmuta said.

"There's a considerable perceptual element for these sorts of things."

Agricultural runoff, types of vegetation, animal activity and household fittings can also change the taste.

What's tap water like across the country?

According to Western Sydney University water scientist Ian Wright, Perth and Adelaide's drinking water is often considered the worst.

"Australia really is the most water-deprived continent, and Adelaide and Perth really cop it," he said.

Melbourne has the country's lowest levels of salt in their drinking water, while Perth fared worst. ( Supplied: Dr Ian Wright )

Water in those two cities is saltier than the rest of the country, when measured in total dissolvable solids (TDS) in milligrams per litre.

Adelaide has to grapple with being at the end of the Murray River, where water picks up different organic and inorganic contaminants on its way to South Australia.

"Even Canberra's toilets discharge into the Murray-Darling River, so farmer's livestock, humans, mining, that can all release and mobilise contaminants into their water," Mr Wright said.

Adelaide gets the bulk of it's water from the end of the Murray River. ( ABC News: David McMeekin )

Meanwhile, he said Perth is "getting on 45 years of drought", creating a reliance on groundwater, which generally has a higher salt content than water from catchments.

Mr Wright's research shows Melbourne, Darwin, Canberra and Hobart have the least salty water.

How does Tasmania's boast stack up?

The Apple Isle has a good reputation for its fresh water, with H2O from Barrington in the state's north even winning the best tasting water in Australia at the 2016 Water Industry Association of Australia awards.

Mr Wright said Hobart has very pure water, and that's mostly because of the rocks.

"The catchments around Hobart have a lot of really old basalt and granite geology and that creates a very pure sort of water."

"It has more H2O in it than anything else," he said.

Water from Tasmania's Lake Barrington won the prize for Australia best tasting water in 2016. ( Discover Tasmania )

But Mr Stapleton said water quality does vary depending on the catchment.

"We collect water from 70 catchments statewide," he said.

"Lake Barrington is pristine, while Esk rivers and parts of the Derwent River are highly impacted — so it all has to be brought up to standard."

Taswater has a designated taste panel of certified tasters that have been trained to instantly identify specific chemicals, even at very low levels, which Mr Stapleton said are almost as accurate as testing in the lab.

Following years of parts of Tasmania being forced to boil their water for fear of bacteria, Mr Stapleton said there are no more boil water or do not consume alerts statewide.

So is Tasmania's water the best?

It's hard to say it's the best, but it's certainly pretty good.

Melbourne is the stiffest competition, with slightly less salt and a lot of loyal followers.

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In response to the social media poll, punters in the comments voted in favour of the water in Victoria's capital city.

"Tassie water is very good, but the best water in Australia is Melbourne water," Eric Lehtonen said.

Jamie Watson agreed, saying: "Have you tasted Melbourne water? Plus it's not cold out of the tap like it is in Tassie."

But there was plenty of support for the island state's water, including from Mr Wright.

"I've been down to Tasmania to study lakes and rivers and you've just got so much more beautiful water than the rest of water-deprived mainland Australia."

"Australia has great water generally, but Hobart's is better than most."