In the final article of the Science drought special, Megan Mullin of Duke University looks into public water supply fragmentation, and why it matters for drought resilience.
Nationwide, an estimated 87% of Americans receive their drinking water from a community water system.
(A “community water system”" just means public water supply.)
I initially read this as: “87% of folks are well protected against drought.”
Because public utilities usually tap multiple use water sources, have a reliable funding stream for infrastructure maintenance and development, and are able to mobilize emergency funds to pump or even tanker water if necessary. Also, if there’s a threat of shortage, then it’s the commercial and industrial users that will go without water. Shutting off public water supply does not go down well with voters.
Water service is highly fragmented: of the 50,000-plus [community waters systems] delivering drinking water year-round, more than 80% provide service to fewer than 3300 people.
The good stuff I listed above doesn’t apply when your supply system is really small:
[utilities] with smaller, lower-income customer bases have less political influence in the state-, regional-, and watershed-level institutions that determine allocation priority, even when those institutions are designed to plan more proactively for drought contingency. Resource and information constraints can hinder participation in allocation processes, and decision-makers at these [systems] might perceive a stronger tension between sustainable management of the water resources and the imperatives of economic development. Because water service provision is funded overwhelmingly through user fees, small systems and those serving disadvantaged communities have less fiscal capacity to maintain robust infrastructure that minimizes leakage and protects water quality during periods of scarcity, especially if their customer base does not include major commercial users. These systems are also less able to make investments in response to detection of operational weaknesses.
During the 2011–2017 drought in California, nearly 150 CWSs serving an estimated 480,000 Californians experienced water shortages or requested emergency funding from the state in order to maintain water service.