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ANALYSIS: Does it really take 11 litres to bottle 1 litre of water?

Scenes of frantic bottled water buying in Cape Town followed the January 2018 announcement that “Day Zero” - when the city would no longer be able to supply piped water - was imminent.

On social media, residents started sharing water-wise strategies thick and fast. And it helped, as the city declared in March that Day Zero “will not occur in 2018”, provided that residents keep saving water and that “decent” winter-rains fall.

One water-saving suggestion posted on the Cape Town Water Crisis Coalition’s Facebook page was for residents to skip the bottled water aisle, as “it takes 11 litres of water to produce 1 litre of bottled water”.

A reader suggested we investigate. Fatima Shabodien, the original poster of the content, told Africa Check that the post had originally been written in 2012 for internal purposes at ActionAid, where she serves as the country director for South Africa.

“Unfortunately, I do not recall the source for the 11 litres,” Shabodien noted.

‘It really depends on the process’

Claims about the quantity of water needed to produce a bottle of water have varied. Some estimated it at 8 litres per one litre bottle, while others claimed that 2.33 litres of water go to waste during the filtration process to bottle 1 litre of water.

Shabodien herself said to Africa Check that “now, the figure seems to differ significantly across different sources”.

So what is the true cost of a bottle of water in water terms?

“The amount of water it takes to produce bottled water really depends on the process that is used to make sure that the water is safe to drink,” Kirsty Carden told Africa Check. She is a faculty member of the Urban Water Management research unit at the University of Cape Town.

If water is bottled straight from the source then very little extra water would be used, Carden told Africa Check. But if water needs to be treated through processes like reverse osmosis, deionisation or ultrafiltration, the quantity of water required increases.

(Note: Chief executive of the South African National Bottled Water Association, Charlotte Metcalf, told Africa Check that “these treatments are not allowed for ’natural water’ or ‘water defined by origin’, which accounts for 90% of SANBWA members' production”.)


Three kinds of bottled water in SA

Bottled water regulations stemming from the Foodstuffs, Cosmetics and Disinfectants Act distinguish between three types of bottled water.

  1. Natural water is sourced from a natural or drilled underground source and is then bottled near that source. Treatment for this type of water includes removing unstable compounds such as iron manganese and sulphur by means of decantation or filtration. The South African National Bottled Water Association claims approximately 70% of bottled water in the country falls under this category.

  2. Water defined by origin is sourced from water originating from specific environmental sources, like icebergs, snow, rivers and streams. About 20% of bottled water is said to fall under this category.

  3. Prepared water has undergone treatment which alters its original properties. Treatment includes reverse osmosis and ozonation. Sources for this type of water include underground and municipal water. Approximately 10% of South Africa’s bottled water falls under this category, according to association figures.


Source: South African National Bottled Water Association

Water footprint - similar to a carbon footprint

“But of course that is only part of the issue – it also takes water to produce the bottles for bottled water,” Carden added.

To take account of the entire production process, a water footprint assessment is conducted. A water footprint helps people understand how much water it takes to produce goods, water and sanitation expert Richard Holden told Africa Check.

“The whole idea is like with the carbon footprint; it’s just to get people to have some idea of the impact they’re having,” Holden said. “If you buy lettuce in the supermarket and you allow it to go rotten and chuck it out, you are throwing away water.”

The concept was introduced by Arjen Hoekstra, a water management professor at the University of Twente in the Netherlands, in 2002. He was trying to quantify the water used in the production process of agricultural and industrial products.

Hoekstra now serves as the chair of the Water Footprint Network, a collaboration of academics and industry experts who promote “science-based, practical solutions and strategic insights to transform the way we use and manage our water resources”.

Industry: 1.6 litres for every 1 litre bottled

  Africa Check conducted a makeshift experiment to calculate the water footprint of a litre of bottled water." />

But water footprint assessments are not done regularly in the local bottling industry, Charlotte Metcalf, chief executive of the South African National Bottled Water Association (SANBWA), told Africa Check.

“The industry is too small - more importantly, SANBWA as an organisation is too small - and the budget to do so is not there,” she said.

Metcalf says the few assessments SANBWA have conducted shows an average water usage figure of 1.6 litres for every 1 litre of bottled water produced by the organisation’s members. She explained that the 600 ml contribute towards cleaning and sanitation of the plant together with things like flushing toilets.

As for the water used to make the plastic bottles, Metcalf didn’t have figures available. Neither did Plastics SA or the plastic recycling company
PETCO which she referred us to. (Note: PETCO referred us to Extrupet and Mpact Plastics, which also did not respond.)

In the absence of local information, Metcalf directed us to a 2011 report by the Beverage Industry Environmental Roundtable, which provides “default data” for North America and Europe.

This showed that to make 1 kg of Polyethylene Terephthalate (PET) resin – the material required to make plastic bottles – 60 ml of water would be required. The blow-moulding process by which the resin is then turned into bottles requires 40 litres of water per kilogram of PET bottles.

This excludes the production of the bottle cap, however. To make 1 kg of the raw material required for bottle caps (high-density polyethylene or HDPE) would require 29 litres of water.

A back-of-the-envelope calculation

Africa Check conducted a makeshift experiment using a kitchen scale and a 1 litre Valpré bottle. The bottle weighed in at 34 g, but the cap didn’t register on our low-tech scientific instrument (we’ll calculate it at 1 g, for argument’s sake).

Using the old, international statistics and inexact weights, 1.4 litres of water are needed to produce the plastic bottle and cap. Adding it to the 1.6 litre industry figure means producing 1 litre of bottled water would require just over 3 litres of water - with much giving and taking, of course.

But where does the water come from?

In the end, “the actual number is only part of the story”, Prof Henry Jordaan, head of the Agricultural Economics School at the University of the Free State, told Africa Check.

“If you do a water footprint assessment you must also look at the sustainability. So you look at where the water comes from and what the water situation is there.” (Note: SANBWA stated in a document that all their members in the Western Cape province use groundwater as their water source. Before membership is granted, their water source is audited by independent underground hydrologists to ensure long-term sustainability, Metcalf told Africa Check.)

While people may not have thought about the source of their water much before, Cape Town’s water crisis has certainly brought it to the fore.


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