The massive spike in Cape Town’s bottled water sales, which increased by 118% in December and January after the announcement of Day Zero, has dropped drastically and some outlets are selling stock at half-price to clear the shelves.

The decline in sales appears to be primarily because Day Zero has been pushed to next year, so there is no longer "panic buying", but also because many Capetonians who have the money have become more water self-sufficient since the advent of the crisis, and have installed rain water tanks and sunk boreholes.

A shop in Fish Hoek is now selling 5-litre bottles of water for R10.

Shop staffer Edgar Valentine said, at the height of the Day Zero panic, the shop was selling between 50 and 70 bottles a day for between R17 and R20 each.

"We got in extra stock in because of Day Zero, but now because Day Zero is further away, sales have dropped off, so we are selling them at R10 to get rid of the old stock," Valentine said.

Shoprite said this week that there had been "a steady decline” in monthly bottled water sales since the spike during December and January, which had shown a 118% increase compared to the same period the previous year.

Pick n Pay said the demand for bottled water in the Western Cape had now dropped to the same levels as other regions.

Brian Austin, Pick n Pay’s head of groceries and perishables, said there had been a "significant" increase in bottled water sales in the Western Cape after the announcement of Day Zero. Now, "given the deferring of Day Zero and early stocking up by customers, demand has since normalised", he said.

'The hype is over, and our stockpile’s gone'

Chan Pillay of Woolworths Food said demand for bottled water had "increased dramatically when Day Zero was announced", but there had been a decline in sales after the Day Zero had been averted.

News24 asked some Cape Town residents whether they still stockpiled water. Most said they now kept just a few 5-litre bottles.

Rob Byram of Kenilworth said, at the height of Day Zero, the family had a 100-litre stockpile.

"The hype is over, and our stockpile’s gone. But we are still buying about four 5-litre bottles a week, because my daughter doesn’t like the taste of tap water anymore. We never used to do that," Byram said.

Briony Robertson of Rondebosch is slowly using her stockpile of 120 litres, bought in January after the City announced Cape Town’s taps could run dry.

She will replenish some of it, because she does not believe Day Zero has disappeared completely, but won’t stockpile in bulk again.

"The main reason is that we’ve installed a rainwater tank so we can store 5 000 litres of rainwater, which will keep us going for quite a bit. So I am not too concerned about keeping bottled water stockpiled anymore," Roberston said.

Will bottled water go off?

Robertson said, since the start of the severe water restrictions, her daughter had been required to take five litres of water to her crèche every Monday. They have been using their stockpile for that, and then refilling the bottle with tap water for several weeks before recycling it.

Robertson said it had not been easy to get hold of bottled water in January when the panic set in.

"One shop let us put our name on a waiting list. Other places, it was just first come, first served, but they restricted how many bottles each customer could buy."

She knows some people who bought 50 or 100 boxes, each containing four 5-litre bottles.

"Basically, we just needed enough to get us out of the city, because I thought the schools would be impacted on and if they were, there was no way I was going to hang about because neither of us has jobs that limit us to being in Cape Town."

Some people have questioned how long it is safe to keep water bottled in plastic.

Charlotte Metcalf of the SA National Bottled Water Association (SANBWA), representing 80% of bottled water in South Africa, said no one with stockpiles of bottled water that bore the SANBWA logo need fear the water would "go off".

"Although packaging discloses a 'best before' date, as long as the water was purchased from a SANBWA member of other reputable bottler, and the seals remain intact, the water can be stored for extended periods. Of course, common sense must prevail. It should be stored in a cool, dark place preferably away from sunlight," Metcalf said.

Million plastic bottles sold worldwide every minute

Research by the State University of New York released this year found an average of 10 plastic particles per litre in bottled water, larger than the width of a strand of hair. Researchers tested 250 bottles of 11 different brands bought in nine different countries, of which 93% showed some microplastic contamination.

This was twice as much plastic as had been found in tap water in an earlier study released in September.

The study said the health effect of this was not known.

City of Cape Town spokesperson Luthando Tyhalibongo said residents should adhere to the expiry dates on bottled water.

He urged residents to reuse plastic bottles and to recycle them, so they did not end up in landfill sites.

Only 65% of PET plastic bottles are recycled in South Africa and 50% globally, of which 7% are turned into new bottles.

One million plastic bottles are sold worldwide every minute.

The UN has said plastic pollution in the oceans has reached a stage where microplastics – pieces smaller than 5mm – now outnumber stars in our galaxy.

Tyhalibongo said the City was unable to predict how much the dams would be filled this rainy season, so urged residents to stick to 50 litres a person a day.

Rain has boosted Western Cape dam levels to 32.1%. This week in 2017, dam levels were 20.9%; in 2016 they were 29.6%; in 2015 they were 50.7%; and in 2014 they were 85.9%.