Water Poverty Index (WPI)

The Water Poverty Index (WPI) is a composite indicator used to assess water scarcity and vulnerability in communities and countries by integrating both physical water availability and socioeconomic factors. It was developed by Caroline Sullivan and colleagues (published in 2002), and it supports decision-making and the prioritisation of investment to improve water security and sustainable access to safe water.

Components of the WPI

The index combines five components, often weighted equally but adjustable to local context:

1. Resources (R): renewable water availability per capita.
2. Access (A): the share of the population with access to safe drinking water and sanitation.
3. Capacity (C): socioeconomic indicators (such as income, education, and health) that reflect the ability to manage water.
4. Use (U): patterns of water use across agriculture, industry, and households, including efficiency.
5. Environment (E): environmental quality and the integrity of aquatic ecosystems.

How it is calculated

In its simplest, equally weighted form, the five components are each scored and combined into a single value on a 0 to 100 scale, where lower values indicate greater water poverty. The original study by Sullivan et al. applied the framework to rank a large number of countries, and the approach has since been adapted to regional and local scales.

Applications

• Policy design: identify priority regions for water and sanitation infrastructure.
• International cooperation: help target development assistance for water, health, and poverty reduction.
• Research: explore the links between water availability, poverty, and climate change.

Advantages

• Holistic approach: integrates physical, economic, social, and environmental dimensions.
• Easy to communicate: an intuitive 0 to 100 scale for policymakers and the public.
• Comparability: enables comparison across places and over time.

Limitations

• Data quality: socioeconomic indicators may be outdated or inconsistently disaggregated.
• Subjective weighting: the weight given to each component can vary by region or methodology.
• Ecological detail: it does not directly capture environmental flow dynamics.

Relationship with other indicators

• Water stress: focuses on physical pressure on resources; the WPI adds a social and institutional layer.
• AWARE and blue water scarcity: assess the sustainability of water use, while the WPI captures multidimensional water poverty.
• Water scarcity assessment: a broader set of methods for evaluating shortage and risk.

Strategies to improve the WPI

• Infrastructure investment: expand water distribution and sanitation networks.
• Institutional strengthening: improve governance and community participation.
• Water-use efficiency: promote precision agriculture and efficient irrigation.
• Environmental protection: restore watersheds and control pollution.

The Water Poverty Index is a useful diagnostic tool for identifying water-related vulnerabilities, guiding investment, and monitoring progress toward SDG 6 (clean water and sanitation). At Manglai we help companies measure their carbon footprint and prepare their sustainability reporting, including water-related impacts. Discover how Manglai can help you.