Resource Adequacy: Water — Paper Rights, Wet Water
The deeds were drawn in a generous year, when the river ran high and the scribes were confident, and every house was promised its share in perpetuity. The parchment did not change. The river did — and when the two disagreed, it was never the river that yielded.
The Other Water Problem
There are two water stories running through this section, and they are almost always conflated. The first is compliance — lead service lines, PFAS limits, a century-old network reaching the end of its life. That is a regulatory capex cliff with a deadline attached, and it has its own piece. This is the second story: scarcity. Not whether the pipes meet the standard, but whether there is enough water in the basin to run what has been built beside it.
The distinction matters because the drivers are unrelated. Compliance risk is created by a rule and resolved by spending. Scarcity risk is created by hydrology and cannot be resolved by spending at all — only relocated, rationed, or engineered around at a cost in energy. A regulator can extend a deadline. A basin cannot extend its runoff.
Two Systems That Are Actually One
The reason water belongs in an infrastructure section at all is that the power system and the water system are not two systems. They are one system, coupled in both directions, and neither sits upstream of the other.
Power needs water. Thermal generation — coal, gas, nuclear — runs on the steam cycle, and steam must be condensed, which requires cooling. A global assessment of nearly 14,000 thermal plant units totalling some 4,182 GW found freshwater cooling demand to be substantial enough to constitute a first-order sustainability constraint on the fleet. Hydropower is water by definition.
Water needs power. Moving, lifting, treating and pressurising water is energy-intensive, and increasingly so as cities reach further for supply. Every megalitre delivered to a city on a plateau, or desalinated, or recycled to potable standard, arrives as a converted quantity of electricity.
A water shortage is a power shortage, and a power shortage is a water shortage. There is no independent variable.
This is why treating water as an environmental footnote in a power investment is an analytical error. When river flows drop or intake temperatures rise, thermal plants face operational limits — derating or shutting down — and those limits arrive precisely when electricity demand is peaking during a heatwave. The same event constrains supply and inflates demand simultaneously. As with the adequacy piece before this one, these are not independent risks that diversify; they are one event expressing itself on both sides of the balance.
Averages Lie. Basins Are the Unit.
The single most common mistake in water analysis is to reason at national scale. Water is not fungible across geography in the way capital or even electricity is — moving it any meaningful distance or elevation is prohibitively expensive, which means a country can be comfortably water-rich in aggregate and have an asset standing in a basin that is running out.
The correct unit of analysis is therefore the catchment, not the country — and increasingly, the catchment in a specific season and a specific year. That is the discipline this piece exists to establish, and it applies identically to a power plant, a data centre, a steel mill or a semiconductor fab.
The consequence for the build-out is direct: roughly 40% of the world’s data centres are estimated to be operating in regions already facing high water stress. That is not a projection about a future risk. It is a description of the current siting map, assembled over a decade when water was not among the variables the industry optimised for.
For any asset with material water dependence, the diligence question is not “does this country have enough water?” but a sequence of narrower ones: which basin, what is its current stress level, what is the legal seniority of this asset’s claim on it, and who else is claiming the same water? Screening projects against basin-level stress is becoming a standard due-diligence requirement rather than an ESG nicety — and it changes conclusions, because two identical facilities in the same country can carry entirely different water risk.
Paper Rights and Wet Water
The clearest illustration of what water scarcity actually does to infrastructure is the Colorado River, and it is worth walking through carefully because the mechanism generalises.
The river supplies water and hydroelectricity to some 35 to 40 million people across seven US states and Mexico, governed by a body of compacts and agreements collectively known as the Law of the River. That framework allocates 15 million acre-feet annually to the recipient states, plus a further 1.5 million to Mexico. The allocation was agreed in 1922.
Here is the defect at the centre of the system. The 1922 negotiators set those volumes using flow records from what turned out to be the wettest sustained period in the basin since roughly 1520. The entitlements were calibrated to an exceptional river, and written in perpetuity. Everything since has been a slow collision between that parchment and the hydrology.
The 2000–2022 megadrought made the gap unavoidable: reservoir levels fell to their lowest since the dams were built, and the federal government declared the basin’s first-ever water shortage. Rising temperatures alone reduced streamflow by roughly 10% during that period, independent of precipitation. And the operating rules governing how the major reservoirs are managed are expiring now, in 2026, with successor arrangements still unresolved — which means the allocation framework for one of the most economically important basins in North America is, at this moment, an open question.
A water right is a claim on a river. It is not a quantity of water.
“Paper water” is what the entitlement says you may take. “Wet water” is what is physically in the channel this year. Where a basin is over-allocated — where the sum of paper rights exceeds the actual flow — those two numbers diverge, and the divergence is resolved by seniority, by curtailment, or by litigation. For an infrastructure asset, the investable question is never whether it holds a water right, but where that right sits in the queue when the river runs short. A junior right in an over-allocated basin is a liability wearing the costume of an asset.
The New Claimant
Into an already-contested allocation now arrives a new and unusually concentrated demand. Direct water consumption by US data centres more than tripled between 2014 and 2023, reaching roughly 17.5 billion gallons — some 66 billion litres by one national laboratory’s estimate — and is projected to potentially double again by 2028.
Three features make this demand more disruptive than its absolute volume suggests. It is geographically concentrated, landing in specific counties rather than spread across a state. It is seasonally peaked — daily water demand for evaporative cooling can spike six to ten times average levels during peak summer, which is exactly when the basin is tightest. And most of what it withdraws is genuinely consumed rather than returned: in evaporative systems roughly 80% of the water evaporates, and in an interior basin very little of that returns as local precipitation.
The competition this creates is being negotiated in public. In the Colorado basin, federal programmes have paid water users — largely farmers — to fund conservation projects that free up supply, while state regulators have begun setting out negotiating principles for utilities dealing with data-centre developers. One state’s conservation board estimates it must find hundreds of millions of gallons per day in additional supply by 2050 before accounting for new data centres at all.
The Substitution Trap
The obvious response to water scarcity is to stop using water — and the technology exists. Dry and air-cooled systems can cut water consumption dramatically. But the coupling described earlier means this is not a free move.
Air cooling requires significantly more electricity than evaporative cooling to reject the same heat. So an operator conserving water raises power consumption — and that additional power, if generated thermally, consumes water somewhere else in the basin or the next one over. The saving is real but partial, and it converts a water cost into an energy cost. Under water restrictions, systems forced to run hotter also lose efficiency, which compounds the effect.
Saving water costs energy. Saving energy costs water. The only way out is generation that needs neither.
This is the analytical payoff of the whole piece, and it points somewhere specific. The genuine escape from the water-energy trap is generation that requires essentially no water at all — solar photovoltaics and wind, which have no steam cycle to cool. That reframes low-water renewables from a carbon decision into a water security decision, and it is why the strongest argument for renewables in an arid region may have nothing to do with emissions.
The magnitude is not marginal. An assessment of India’s power sector found that an ambitious shift toward renewables combined with improved cooling could cut water withdrawal intensity by as much as 84% by 2030 and consumption intensity by around 25% against a 2014 baseline. Globally, the thermal-fleet study cited earlier concluded that under a best-policies pathway, power-sector water consumption could fall roughly 98% and withdrawal around 95% by 2050. The water problem in the power sector is, to an unusual degree, solvable — by changing what generates the electricity.
Reading It Through the Frameworks
Where is the physical risk mispriced? This is the primer’s first question at its sharpest. Water risk is local, non-linear and legally structured — and it is routinely assessed at national resolution, if at all. An asset’s water position is a function of its basin, its seniority and its cooling technology, none of which appear on a balance sheet. The gap between a documented basin stress level and its expression in an asset’s valuation is precisely the kind of mispricing this section exists to find.
Where does policy become the cash flow? Water allocation is a legal regime, not a market outcome. Seniority systems, curtailment rules and permitting decide who keeps operating in a drought. And the permitting gate is now binding on new construction — in stressed basins, water availability determines whether a project is approved at all, which makes it a siting constraint on par with the interconnection queue.
Where is the moat? In senior water rights in a stressed basin, which are finite, legally protected and cannot be manufactured — the closest thing to an interconnection right in the water system. And in water-free operation, which converts a permitting liability into a siting advantage.
Water scarcity is the constraint most likely to be under-modelled in an infrastructure portfolio, because it is local where analysis is national, legal where analysis is physical, and correlated with exactly the conditions that stress everything else. Power needs water and water needs power, so a drought is never only a water event — it derates the thermal fleet, empties the reservoirs behind the hydro, and raises cooling demand, all in the same week.
Two disciplines carry beyond this piece. Screen at the basin, never the border — two identical assets in one country can face entirely different water risk. And distinguish paper rights from wet water, because in an over-allocated basin the question is not whether an asset holds an entitlement but where that entitlement sits in the queue. The parchment was written in a generous year. The river was not consulted.
They brought the deeds to the water-master in the dry season and asked him to honour them. He read each one carefully, and said that they were all valid, and all of them together promised rather more water than had come down the valley since his grandfather’s time — and that this was a matter for lawyers in a wet year and for no one at all in a dry one.
Leave a Reply