Applied case study · Hypothetical policy
Water Pricing During Drought
Can a city reduce discretionary demand without making basic water unaffordable?
Decision setup
The city below is a teaching scenario, not a report about a named utility. Reservoir storage is declining, metering is widespread, and the utility must cover treatment and network costs. Officials are considering increasing-block prices plus targeted assistance.
Economic mechanism
A marginal price can discourage an additional unit of discretionary use, but response depends on whether users see the signal, can measure consumption, and have practical substitutes. A low-priced lifeline block can protect basic use; it does not automatically reach households facing leaks, large household size, shared meters, or low income.
Efficient pricing also requires a cost definition: short-run operating cost, long-run capacity cost, scarcity value, and environmental effects are different concepts. A tariff that recovers revenue is not necessarily equitable, and a tariff that changes demand is not necessarily sufficient during an emergency.
Worked tariff exercise
Tier 1: first 6 m³ at $1.00/m³; Tier 2: next 9 m³ at $2.00/m³; Tier 3: use above 15 m³ at $4.00/m³.
A household using 20 m³ pays 6×$1 + 9×$2 + 5×$4 = $44, before fixed charges or assistance. Average volumetric price is $2.20/m³; the marginal price of the next cubic metre is $4.00.
All numbers are hypothetical. A real proposal must publish currency, billing period, fixed charges, taxes, household-size adjustments, eligibility rules, and the date from which rates apply.
Evidence plan
Efficiency: Compare weather-adjusted use by customer class before and after the change.
Equity: Track bills as a share of income, arrears, disconnections, leak adjustments, and assistance uptake.
System outcome: Report withdrawals, losses, storage, service reliability, and revenue sufficiency with dates and units.
A simple before/after decline does not prove the tariff caused it. Rainfall, restrictions, public messaging, economic activity, and customer composition may change at the same time.
Stakeholders and failure modes
- Shared or inaccurate meters weaken the price signal.
- High fixed charges can make a “cheap” lifeline tier unaffordable.
- Revenue may fall faster than costs when conservation succeeds.
- Outdoor-use reductions may be easier than essential indoor reductions.
- Unrepaired network leakage can shift responsibility unfairly to customers.
Decision task
Revise the three tiers and add one affordability safeguard, one leakage measure, and one evaluation metric. State which evidence would make you change the policy.
Sources and data boundary
- OECD: Water governance and economics — policy and governance context.
- World Bank: Water — service, finance, and resource context.
- World Bank: Annual freshwater withdrawals, total (% of internal resources) — country-level annual indicator; accessed 9 October 2026.
The withdrawal indicator is not a city drought dashboard and does not set household tariff levels. Use current local utility and hydrologic records for real decisions.