A non-partisan, neutral perspective supporting diversity in the color of water

Friday, September 10, 2010

Greywater and the Real Thing

One topic that the Rainbow Water Coalition has not touched upon is *industrial* greywater. Forbes magazine, among many others, ran this article, where the Coca-Cola Company and The Nature Conservancy announced the release of a water footprint report in conjunction with World Water Week in Stockholm, Sweden. The report, entitled "Product Water Footprint Assessments: Practical Application in Corporate Water Stewardship," examined three pilot studies that were conducted on Coca-Cola products and ingredients.

Research found that the value of a product water footprint is its ability to disaggregate water use by component, allowing both direct and indirect water use to be examined, as well as the different types of water that are used. The types of water are green water, which is rainwater stored in the soil as moisture; blue water, which is surface and ground water; and grey water, which is the volume of freshwater required to assimilate pollutants based on existing ambient water quality standards. Keeping the components of a water footprint separate allows impacts to be assessed in the context of local watersheds where the water is being sourced.

The Company and the Conservancy found that the largest portion of the product water footprints assessed in the pilot studies comes from the field, not the factory.

In partnership with third-party researchers, the Company and the Conservancy calculated the water footprints of Coca-Cola(R) in a 0.5 liter PET bottle produced by Coca-Cola Enterprises Inc. (CCE) in the Netherlands; beet sugar supplied to Coca-Cola bottling plants in Europe; and Minute Maid(R) orange juice and Simply Orange(R) produced for the North American market.

Estimates are that the green water footprint of the 0.5 liter Coca-Cola beverage is 15 liters; the blue water footprint is 1 liter; and the grey water footprint is 12 liters.

The average green water footprint for sugar from sugar beets across all regions of Europe is estimated to be 375 liters/kg sugar; the average blue water footprint is 54 liters/kg sugar; and the average grey water footprint is 128 liters/kg sugar. The size and color composition of the water footprint varies depending on the region from which the beets are sourced.

To download the water footprint report, go here.

I guess there is something to the adage that the solution to pollution is dilution, and greywater is apparently the *diluter* in the field. It sounds like the greywater footprint could be reduced by treating the wastewater *in the field*, somehow transforming the greywater to greenwater again. But that might cause the cost of a bottle of the real thing to increase, not a real good thing in the competitive world of soft drinks.

And the Greywater Gadget of the Week is also industrial sized. According to this article in green-buildings.com, one of the largest HVAC water consumers around is the cooling tower, which cools water through evaporation. Cooling tower water is most often made up for from potable municipal sources. Though, despite increased water usage, cooling towers are an energy-efficient and cost-effective method for heat rejection, and typically include very long equipment lifetimes. The downside is that proper water treatment is also required, to ensure optimal heat transfer, minimize biological growth, scale and corrosion.

Utilization of rainwater, graywater or condensate (the byproduct of cooling or heating processes) in cooling towers is still in its infancy in a way, since these water sources have different chemical make-ups than municipal water. So this requires separate water treatment programs for each makeup water source, and the water treatment for graywater or rainwater systems must act in real-time to modulate treatment depending on the chemical composition of the water.

Aquanomix’s AX-CTI Water Management Center  a state-of-the-art system for rainwater, graywater, and condensate reclamation. Ain't she a beauty!


  1. Todd-

    Great blog! Thanks from the Aquanomix team for the shout.

    All the best,


  2. Thanks for discovering the Rainbow Water Coalition, Sarah. Please keep me posted on where the Aquanomix is used, and I will post a follow-up.