Beer, smokes, nappies and Coke have traditionally driven people to supermarkets.
The world's biggest-selling soft drink in history came sixth on a survey of 3000 people about which big brands they couldn't do without, according to researchers Canstar Blue.
But sales in the highly concentrated soft drink market have been declining in Australia for more than 10 years, and people are opting for water instead.
Bottled water now accounts for more than one-quarter of the non-alcohol ready-to-drink beverages market in grocery stores, according to investment bank Citi, up from 14 per cent five years ago.
And customers are being tempted by the cheaper private-label water sold by the big supermarket chains, Woolworths and Coles. Coca-Cola Amatil has a lower percentage of the bottled water market than it does soft drink.
As soft drink sales volume fall, the prices at which Coca-Cola can sell its cans and bottles are under pressure.
Investment bank Deutsche Bank said soft drink promotions accelerated in the three months to March, with prices falling 5.5 per cent year on year, compared with a 2.7 per cent decline the previous quarter.
???All this is bad news for Coca-Cola Amatil, the country's biggest soft drink company which owns Coke, Fanta, Lift, sports drink Powerade and Zico Coconut Water.
On Friday the company downgraded its half-year guidance due to falling sales in Australia, which accounts for about two-thirds of its market.
As investors raised concerns about the company meeting its full-year guidance, its shares continued to fall on Monday, down 11.7 per cent in two days.
Ian Carmichael, consumer analyst at Watermark Funds Management, nominated a few problems with Coca-Cola Amatil's local beverages arm.
"Private label is taking share in bottled water. Why pay a premium for Mount Franklin when there is no taste difference?" he said.
Water accounts for about 17 per cent of Coca-Cola Amatil's total volume sold, but could account for between 25 and 35 per cent of its earnings, Citi told clients.
"[And] Pepsi/Schweppes have been winning back market share in supermarkets," he said. "Lots of rain in March will have hurt results in the route trade (restaurants, cafes etc)."
Monik Kotecha, chief investment officer at insync fund managers, doesn't contest that Coca-Cola Amatil has challenges ahead but said sentiment would likely turn when Coke's core brands stabilise and growth segments as energy, juice, dairy and tea deliver.
"What's interesting, I think, is there's this focus on health and diet and obesity, but if you look at Monster and Red Bull and even [coffee chain] Starbucks, which has lots of of sugar, they're doing very well," he said.
"Global consumption of sugar has stayed fairly flat. 
"And if you look at Sprite, which is a little different to Coke but still a carbonated soft drink, it had been declining for some time but Coca-Cola came up with a new Sprite campaign in 2016 and it's been growing sales 4 to 5 per cent on an annualised basis."
Analysts have also raised concern about Coca-Cola Amatil's ability to raise prices at the checkout to compensate for increases in the cost of sugar and aluminium.
"The company has still not secured price rises with major supermarkets. While some price rises are likely, we expect some delay and not a full recovery of the raw material cost increases," Citi said.
There are also questions about to what extent declining sales will diminish the company's bargaining market power with the supermarkets.
"As demand for the category reduces Coca-Cola Amatil's bargaining power with the supermarkets also diminishes, in our view," investment bank Morgan Stanley said.
Sales to Australian supermarkets accounted for about one third of the company's earnings before interest and tax, said investment bank UBS.
UBS also flagged the prospect of soft drinks losing space on supermarket shelves, as supermarkets reduce their product range and replace soft drink with water and energy drinks.
"Anecdotally, ranging for carbonated soft drinks has been in decline across supermarkets for some time, largely at the expense of water and energy," it said.
"Looking forward we believe this could accelerate through 2017-18, particularly as soft drink products are moving to every day low pricing ... and Coles, in particular is looking to reduce range by 10 to 15 per cent.
"While Coca-Cola Amatil enjoys strong brands, the dominance of Coles and Woolworths in the grocery sector is limiting margin."
