On the water literacy and distributive risks of GCEW’s ‘new’ drop of water

The 2024 Global Commission on the Economics of Water (GCEW) says we can create a new water drop by improving the recycling of water in two of its five missions, # 3 and 4. Here is a quote that covers both, on page 115 of their main report: “Establish a circular water economy, including changes in industrial processes, so that every drop of used water generates a new drop through reuse.”

Without undermining the importance of the GCEW missions 3, 4 and 5 on urban, industrial and WASH uses of water, let us look at whether a new water drop is generated through improved recycling of wastewater. l also look at who gets this extra drop through a framing I call the paracommons (Lankford, 2013, Lankford, 2014, Lankford and Scott, 2023). The paracommons is a commons of (or competition for) redistributed water following changes made to withdrawals, efficiency gains and recycling, amongst other management changes. (N.B. It can also ask who gets the gains from storage gains).

Here is some of the text in the footnote at the bottom of page 125 of the GCEW report explaining how a new drop is generated from water treatment and recycling. “To illustrate, recycling 50% of the water supply once will result in every drop of used water producing 0.5 drops of usable water. This 0.5 drop of “new” usable water will then produce another 0.25 drops, then 0.125 drop and so on. Theoretically, one drop of used water will produce another drop of water (i.e., 0.5 + 0.25 +0.125 + 0.0625 +…= 1), which is a multiplier of 2.”

So, according to the GCEW and their calculation, water recycling produces new drops. (NB, the term ‘new drop_’ is found six times in the main GCEW report).

Is this calculation water-literate, and does it support two of five missions on a new circular approach to water? Note, the GCEW report in Section 9 also says water data and accounting must be part of a better future of water management. I agree; we can only establish a new era of water management based on well-designed, fully debated, accurate water accounting.

In the spirit of the GCEW’s thought-provoking and horizon-scanning report, I hope this blog contributes to the discussion on these matters. Using this linked spreadsheet, I would like to illustrate several concerns about new drops created from water recycling. The Excel file conducts calculations on a cubic metre of water which represents a drop of water. The image below is part of this spreadsheet. The spreadsheet contains eight calculations or Cases which, from 1 to 8, layer up complexity. The red arrows show water apportioned to different dispositions within each position or party, and the blue arrows show water flowing from one upstream position to the next downstream position (e.g. from A to B). The yellow highlighted cells show where key changes have been made. To keep the spreadsheet simple, changes to process ratios in the Position A (or the Proprietor) are mirrored in the other three positions/parties. Hopefully, by downloading my spreadsheet and starting with the simplest Case 1, you can follow my arguments.

Case 1 reproduces the footnote text at the bottom of page 125 of the GCEW. It shows the multiplier effect approximating towards 2. Compared to the Cases 2 to 8, Case 1 is very short on detail. Using this simple calculation, the GCEW authors demonstrate that recycling water generates a ‘new drop’ – central to two of the GCEW’s missions. My concern here? Should we be building a new global emphasis on water recycling without defining what we mean by a new drop, without more detailed water accounting, and without adding in regulatory dimensions, amongst other considerations.

Case 2 produces a multiplier effect of 4 in a free-flowing river. By having four positions in a natural stream, the same drop (or cubic metre of water) is non-consumptively (re)used four times (for fish, frogs, fun and flushing). Supporters of ecological flows can now argue a drop of water in a river is extremely beneficial! In fact, because instream non-consumptive use occurs every single centimetre of a river’s flow from its spring to its delta, there are thousands if not millions of new drops being created – all from the same drop. This accounting trick, if I may call it that, should raise eyebrows.

Case 3 also shows that with 100% withdrawal, 100% non-consumptive use and 100% recycling creates a multiplier of 4. This calculation delivers the same benefits as the natural river in Case 2, producing 4 drops out of 1 drop. The more positions of perfect abstraction and recycling, the higher the multiplier effect. If you have 10 positions, then ten new drops of water are created. To my mind, Cases 2 and 3 place a question-mark over the water literacy of a new drop created.

Case 4 reproduces Case 3 but shows that, with 85% withdrawals, 60% consumption, and 50% recycling, I can ‘only’ achieve a multiplier effect of 2.45. And if I adjust cell C32 to 100% recycling (which is what the GCEW is arguing for), then the multiplier effect is then 2.81; not much higher than 2.45 and nowhere near 4.0. Why is this calculation not delivering 4 new drops? Because this system is more akin to what we find in the real world, with its mix of withdrawn and non-withdrawn water, mix of consumptive and non-consumptive use, and mix of recycled and non-recycled (non-recovered) water. And the simplified calculation in Case 4 is nothing like the real world (let alone Case 1 from the footnote of the GCEW report).

Cases 5 to 8 get to the nitty-gritty of the distributive effects of changes in water withdrawals, efficiency and recycling, asking who gets ‘the new drop’. The Cases use elementary water accounting to reveal the paracommons. Cases 5 to 8 exchange the four positions (‘A to D’) to the four parties in the paracommons; ‘the proprietor, immediate neighbour, society and nature’. The proprietor is first in line and can effect changes to its water withdrawals, efficiency of conversion to beneficial use, recycling and so on. The neighbour is immediately dependent on what the proprietor does. Society gets its water next and then last of all nature gets the residual water. Note water for nature, being last in line and not easily distinguishing between beneficial and non-beneficial use, is the sum of the beneficial consumption + the recycled water + the non-recovered, non-beneficial water. Other paracommons models have nature and society on a more even-footing, subject to a purposive division of the water not depleted by the proprietor and neighbour (Lankford and Scott, 2023). There are no red and blue arrows in Cases 5 to 8 to keep our eyes focussed on the numbers.

Case 5 reproduces the same numbers as Case 4 but for clarity’s sake Case 5 is the baseline set of water accounts which Cases 6, 7 and 8 employ to derive differences. These Cases (5 to 8) show how changes in consumption and recycling water benefit different paracommoners by comparing the ‘after’ scenarios (Cases 6 to 8) against a ‘before’ case (aka the baseline Case 5).

Case 6 raises the proprietor’s beneficial consumption ratio from 60% to 90% which raises amount of units consumed within the proprietor. This occurs by having more efficient processes for example by creating less waste within the proprietor and/or by recapturing water within the proprietor (these are not shown in the spreadsheet as their own process). When the proprietor gets the extra 0.255 units of beneficial consumption (BC), which is a 50% gain from the baseline, the three other parties see their BC water amounts decrease by -14%, -50% and -81%. The story of Case 6 is that the proprietor gets the gain of the more efficient internal recycling.

Case 7 keeps the beneficial consumption of the proprietor at 60% same as Case 5, but an improved downstream recycling efficiency of the non-consumed water goes up from 50% in Case 5 to 80% in Case 7. This improved downstream recovery sees the three downstream paracommoners (neighbour, society, nature) get the material gain of changes occurring within the proprietor. The final BC dispositions compared to the baseline are: the proprietor sees no change in the beneficial consumption of water, the neighbour gets a 32% increase in BC, society gets 74% more and nature gets 129% more. Case 7’s story is that with improved process ratios of downstream recycling, water allocations for the neighbour, society and nature all increase. Case 7 supports the GCEW’s assertion of the benefits of enhanced recycling. But please read on.

Case 8 sends more water downstream from the proprietor but does this by cutting the withdrawals into the proprietor to 57% (plus 57% cuts apply to the withdrawals of the others). This withdrawal amount of 57% was found using Excel’s goal-seek after setting the efficiency of the proprietor to 90%, the same as Case 6. The goal-seek solution produces 57% withdrawals to give the same BC in Case 8 as Case 5; in other words zero change in BC. The final accounting outcomes compared to the baseline are: the proprietor sees no change in the beneficial consumption of water, the neighbour gets a 43% increase in BC, society gets 103% more, and nature gets 93% more. Case 8 shows that improved efficiency in the proprietor, mirrored by reduced withdrawals, allocates more water to the neighbour, society and nature. Moreover, importantly there is no need for enhanced recycling in Case 8 since all the water passes linearly from upstream to downstream parties by not being withdrawn in the first place.

Some take-aways:
• In Cases 3 to 8, NO new drop is created. The single 1 cubic metre is distributed across all four positions or parties to different dispositions. See the red text entry at the bottom of each Case, and press F2 to get the cell calculation. There is 1 cubic metre at the start, and 1 cubic metre at the end.
• We must define what is meant by a ‘new drop’, and be careful of suggesting a new drop is a physical new drop. There is a difference between a stock and a flow. The stock of 1 cubic metre is not added to, but with recycling, a flow of 1 cubic metre can be non-consumptively (re)used several times over.
• Be careful of assuming that high water multipliers (that occur with fully withdrawn, fully recycled and fully non-consumptive water) translate to high multipliers in mixed systems comprising partial withdrawals, recycling, some consumptive and some non-recovered water. There are fewer opportunities for ‘new drops’ in the latter systems.
• We should where possible compare an ‘after’ scenario to a ‘baseline’, and compare different before-and-after scenarios.
• We should use better modelling and empirical information to work out the distributive effects of changes to efficiency and recycling, asking which party materially gains from these changes.
• Be careful of over-egging the benefits of a circular water economy compared to the “linear model of water management” (GCEW 2025 page 124). Both have their place. Note, Case 8 provides a pareto-equivalent outcome for the proprietor (BC change = 0) and generates a ‘linear’ downstream allocation of water. It does this by cutting the proprietor’s withdrawals and raising its beneficial consumption ratio.
• We should not forget that when it comes to the food industry, e.g. beverages, the consumptive use of water in a bottling plant is a fraction (I estimate <5%) of the embedded water consumed in the growing of the crops that went into the beverage.  So saving 10% of water in a bottling plant is a ~0.5% water saving in the whole production chain.  Thus, I hope the GCEW is not pointing the new era of water management towards the relatively achievable but volumetrically small wins in urban/industrial recycling away from the more difficult but larger wins in irrigated agriculture – which, if done right, will shift much-needed water to cities and towns, and to freshwater habitats.

• Recycling is not a get-out-of-jail-free card. Water recycling may bring financial and energy costs, plus negative impacts for water timing, temperature, quality and placement. It may be better to improve the management of the linear model to keep water where we want it, rather than to divert it, use it, then recycle it, then put it back to where we want it.
• We need to think through who owns the past-recycled drop, the currently recycled drop and the future ‘yet-to-be-recycled drop’. If the proprietor making the internal recycling investment is not legally and materially held to account, we should not be surprised if the proprietor consumes more water, leaving its neighbour, society and nature with less water.
• When we change the management of the quality and quantity of first-use water and recycled wastewater, we need to specify how various water fractions are technically, spatially, temporally, economically and institutionally controlled, where the new water dispositions end up, and how that redistribution has impacted different parties.

Final four messages

First, recycling and cleaning up wastewater (using renewable energy), and putting this water back to where we want it, will usually create improved social, economic and environmental benefits. But if we make water recycling too beguiling and simple, we run the risk that the material gains from recycling (and other management changes) will be distributed to (captured by) the proprietor and first movers making recycling investments. Without safeguards, the sectors / groups least likely to see their water allocation increase from improved water recycling include the environment, and marginalised urban and rural people. Putting too much emphasis on circular water also risks not seeing the advantages of linear management of water and water allocation.

Second, it has taken years for irrigation actors to get their heads around irrigation efficiency, gains, paradoxes, water recovery, water accounting and the distributive effects of changes in supply and demand management. To my mind this polarised debate remains poorly informed by simple theorisation, logics and calculations. Let us not make the same mistakes with urban and industrial water recycling; someone owns the drops involved; recycling does not create a wholly new material drop; and recycling is likely to redistribute water to different parties creating new winners and losers. Page 17 of the GCEW report rightly states that water saved in recycling water could be directed towards conservation (presumably meaning the environment, given water conservation has another meaning). However in the same paragraph, the word ‘regulations’ pertains to public safety rather than governing who and what owns and gets the saved water.

Third, there are people who say you can’t save irrigation water (because you should not reduce crop BC and everything else gets recycled), and there are people who argue new water drops are created from recycling. I don’t deny some examples of their claims exist, but it is important their arguments, spreadsheets and models are sufficiently detailed to explain their claims, and how useful and generalisable they are. (To say nothing of the dire need for empirical data from cross-scale hydrological research to inform these models and debates – a gap I also face).

Finally, here is what I think is a more water-literate version of the quote from page 115 given above; “Establish a circular water economy, including changes in industrial processes, so that every drop of non-consumptively used water generates a new drop of benefit through reuse.” It’s not perfect, but it retains the precious sense of a water drop – which is what the GCEW and others rightly encourage us to think about.

— 0 —

Thank you for reading, and happy scratching of heads! I invite anyone to criticise me and tell me my water accounts and terms are wrong. They could be. Compared to my other spreadsheets and texts on this matter (e.g. Lankford, 2023), everything here is pretty basic and simplified. Plus I’ve only created eight Cases to explain some of my doubts about the circular water economy and creating new drops of water. There are many more permutations with the linked spreadsheet, and indeed other models about water recycling and efficiency.

How to cite this blog:-
Lankford, B. A. On the water literacy and distributive risks of GCEW’s ‘new’ drop of water. https://brucelankford.org.uk/2024/11/05/on-the-water-literacy-and-distributive-risks-of-gcews-new-drop/

References

Lankford, B. 2013. Resource Efficiency Complexity and the Commons: The Paracommons and Paradoxes of Natural Resource Losses, Wastes and Wastages, Abingdon, Routledge.
Lankford, B. A. 2014. The Paracommons of Salvaged Water. The Land.
Lankford, B. A. 2023. Resolving the paradoxes of irrigation efficiency: Irrigated systems accounting analyses depletion-based water conservation for reallocation. Agricultural Water Management, 287, 108437.
Lankford, B. A. & Scott, C. A. 2023. The paracommons of competition for resource savings: Irrigation water conservation redistributes water between irrigation, nature, and society. Resources, Conservation and Recycling, 198, 107195.