Water is still, by a wide margin, the cheapest utility on your monthly statement. That is exactly what makes a new finding from Stanford University so unsettling: climate change alone could nearly double what a typical household pays for water by the middle of this century and, in some American cities, push more than a third of all households past the line where water stops being affordable.
The research, published July 8, 2026, in the peer-reviewed journal Nature Sustainability, is the first study to connect the dots all the way from shifting rainfall and rising temperatures through reservoir levels, utility construction decisions, and municipal financing to the actual number printed on a household’s bill.
The team, led by Jennifer Skerker at Stanford’s Doerr School of Sustainability, modeled a California coastal city, Santa Cruz, in detail. Their conclusion is a wake-up call for a problem most of us assume lives in the far future or in someone else’s drought.
A Water Bill That Could Nearly Double
Santa Cruz depends on locally sourced surface water for roughly 95% of its supply, anchored by a single reservoir that holds about a year’s worth of water. It is, in other words, a city with very little margin for error.
The researchers paired future climate scenarios from the CMIP6 ensemble with a stochastic weather generator, ran them through a water supply model, and then layered utility adaptation decisions, infrastructure financing, rate design, and household demand on top. The results were stark.
In the “baseline” scenario, a moderate, cool climate similar to today, the median monthly water bill sits at about $64. Under a dry, hot climate where new infrastructure is built as needed, that median bill rises to $120. For households in the 80th percentile, bills climb from about $100 to $204 a month.
For low-income households, defined in the study as those earning under roughly $39,900 a year, the median bill rises from about $60 to $111 per month, and 80th-percentile bills jump from $92 to $186.
Who Gets Priced Out
The U.S. Environmental Protection Agency recommends that households spend no more than 2.5% of their income on water. Today, 19% of Santa Cruz households already exceed that threshold. Under a moderate, warmer climate with adaptation, the share rises to 26%. Under a dry, hot climate, it reaches 35%.
In raw terms, the study estimates that climate change alone could leave an additional 7 to 16% of households with unaffordable water.
The burden lands unevenly. Median low-income affordability burdens rise from 3.9% of income today to 5.1% under a moderate climate and 7.3% under a dry one, with 90th-percentile burdens climbing from 16% to 30% of income. As Fletcher put it in a video released with the study, “If you’re already struggling to pay your water bill, and now it’s going to be double what it was before because of climate change, you’re going to really have a problem making ends meet.”
Why Drought Turns Into Dollars
The chain from rainfall to rate hike runs through concrete and steel. When reservoir storage falls, utilities face a choice: cut demand, or build new supply. Santa Cruz has already squeezed most of the easy demand-side savings. Decades of drought experience and aggressive conservation have left per-capita usage unusually low, a phenomenon engineers call demand hardening.
What’s left is expensive supply expansion: seawater desalination, direct potable reuse, aquifer storage and recovery, or large-scale transfers. In the model’s dry-climate scenario, declining storage triggers construction of a 4-million-gallon-per-day desalination plant, and the cost flows straight through to ratepayers.
The study found that under a dry, hot climate with adaptation, more than half of all months require over $1 million in additional costs just to maintain reliable supply. Under the moderate climate, 60% of months require no new supply costs at all. The difference is not subtle, and it lands hardest on the households with the least room in their budgets.
The driver, once they decomposed it, was not primarily temperature. It was declining average precipitation, followed by increasing precipitation variability. Warmer temperatures played a moderate role by increasing evapotranspiration and nudging demand higher, but supply-side effects dominated.
A National Trend, Not a Local Anomaly
Santa Cruz is a case study, not a national average. But the underlying pressure is nationwide. U.S. household water and sewer bills rose 5.1% in 2025, the steepest annual increase in five years, with a cumulative jump of 24.2% since 2020 according to Bluefield Research’s annual rate index. Over the longer arc, water prices climbed 207% between 2000 and 2025 while overall inflation rose 93%.
Climate change and drought are not the only forces at work. Aging infrastructure, deferred maintenance, and emerging contaminants requiring advanced treatment are all pushing rates up. But as the Stanford team notes, conventional affordability projections extrapolate historical trends without analyzing specific future cost drivers. Climate change is precisely such a driver, and adding it changes the picture.
This isn’t the only way a warmer planet reaches into household budgets. Wildfires driven by hotter, drier conditions carry enormous and lasting costs for consumers, and water-intensive industries are already being forced to adapt, as Texas green ammonia producers facing drought and desalination needs have discovered. Water bills are simply the most direct, most monthly expression of the same underlying stress.
Are We Running Out of Water?
It’s one of the most-searched questions in the water space, and the honest answer is nuanced. The planet is not running out of water. What is changing is the reliability and cost of delivering the right water to the right place at the right time in a climate that no longer behaves like the one our infrastructure was designed for.
In Santa Cruz, the modeling showed cities with larger reservoirs and access to multiple or cheaper water sources may not face the same pressure. The likely national scenario is not a uniform crisis but a patchwork: affordability hotspots concentrated in places where water sources are limited, storage is thin, and income inequality is high.
The researchers also stress that Santa Cruz is not presented as representative of all cities. It is presented as illustrative of a class of urban water systems where climate stress intersects with constrained adaptation options and existing inequality and as a plausible future state for systems that have already used up their cheapest options.
What Cities and Policymakers Can Do
The study’s clearest structural conclusion is that under current U.S. financing models, climate adaptation pits affordability against reliability, even though both are essential for water access.
The team tested three planning strategies. A risk-averse approach that built large desalination capacity early delivered 98.8% average annual reliability but added at least $9.4 million per year in costs and pushed 80th-percentile affordability burdens to 5.2%. A risk-tolerant approach that delayed investment held new spending to $1.4 million per year and affordability burdens to 2.7%, but its worst-year reliability dropped to just 61%.
Both extremes fail someone. The study’s policy prescriptions point beyond the utility:
- Expanded public financing of adaptation infrastructure, rather than loading costs onto rates
- Regulatory reform of rate design, especially where rules restrict cross-subsidization or income-based pricing
- Targeted assistance programs funded outside of water rates, so they don’t cannibalize utility revenue
- Routine affordability assessments alongside reliability assessments in climate adaptation planning
As the authors write, failing to weigh affordability alongside reliability “risks shifting the costs of climate adaptation onto households least able to bear them, even when adaptation successfully reduces physical water scarcity.”
What Households Can Do Now
Systemic problems need systemic solutions, but there are practical steps households can take today, particularly in drought-prone regions.
1. Check your utility’s assistance programs. Many municipalities, including Santa Cruz, already run customer assistance programs for qualifying single- and multi-family customers. These are chronically under-enrolled.
2. Understand your rate structure. Santa Cruz uses an increasing block tariff, where the unit price rises above certain usage thresholds. If your utility does the same, reducing peak-tier use has an outsized effect on the bill.
3. Invest in efficiency before rates climb. Because demand in already-conserving cities is relatively inelastic, the biggest savings come from households that have not yet made efficiency upgrades. High-efficiency fixtures, leak repair, and drought-tolerant landscaping pay compounding dividends as rates rise.
4. Watch local infrastructure decisions. Desalination plants, reuse facilities, and major transfer projects are rate-setting decisions made years before construction. Public comment periods and rate hearings are where affordability gets defended or abandoned.
The Bottom Line
The Stanford study reframes water affordability as a climate adaptation problem, not just a poverty problem. That distinction matters, because it changes who is responsible and when they need to act.
“This is not a new problem, but it’s one that climate change is making worse,” Fletcher said. “So, I worry about the households that are already struggling.”
Water has been cheap for so long that we treat it as a given. The research suggests that assumption has an expiration date and that the bill for a hotter, drier climate will arrive in the mailbox monthly for decades.
