Water Score methodology
Version 0.1 · October 2026 · public draft
What it measures
The Water Score sums up, in a score from 0 to 100, how exposed an address is to four water-related risks: river flooding, surface-water flooding, drought and restrictions, and water stress.
The higher the score, the higher the risk. Each component can be viewed separately, with its source and the date of the data.
- Very low
- Low
- Medium
- High
- Very high
- 0–20 · Very low
- No relevant exposure in official sources. Routine monitoring.
- 20–40 · Low
- Marginal exposure, for example minor water restrictions or occasional heavy-rain warnings. Worth knowing.
- 40–60 · Medium
- At least one risk at medium level. Review the property documentation and insurance cover.
- 60–80 · High
- Official flood zone or drought phase with restrictions. Review the building's insurance cover and prepare an action plan.
- 80–100 · Very high
- Maximum exposure in at least one source, for example a 10-year flood zone or drought emergency. Priority action.
Data sources
We only use official public sources. Every data point we show states where it comes from and when it was last updated.
| Source | Body | What it provides |
|---|---|---|
| SNCZI | MITECO | River flood zones (10, 100 and 500-year return periods), mapping from the current cycle of the Floods Directive |
| Meteoalerta | AEMET | Heavy rain warnings |
| Municipal maps | Town councils | Surface-water flood risk in urban areas |
| Drought status | Agència Catalana de l'Aigua | Current drought plan phase in Catalonia’s internal basins |
| Drought and scarcity monitoring | River Basin Authorities | Current phase of each basin’s special drought plan |
| Water resource indicators | MITECO · INE | Medium-term pressure on water resources |
The update frequency of each source is shown next to each data point in the app.
How the score is calculated
Each of the four risks is assessed separately and gets a score from 0 to 100 based on its official source.
The Water Score is the weighted maximum of those four scores: a high risk in a single component is not diluted by low values in the others.
Each source is mapped to the 0–100 scale according to its official class. For example, a flood zone with a 10-year return period falls in the very high band and a 500-year zone in the medium band; the exceptional or emergency phase of a drought plan falls in the high and very high bands. The weighting between components is being calibrated on recent events in Catalonia and will be published on this page with version 1.0.
Location
The address is resolved to a cadastral reference through the Cadastre's electronic office (Dirección General del Catastro). When the user provides the cadastral reference directly, that one is used. The accuracy of the result depends on that resolution.
Limitations
- The Water Score reflects the official maps and phases in force on the date shown. It does not predict events or estimate financial damage.
- River flooding (SNCZI) covers all of Spain. Drought and surface-water flooding depend on the basin and the municipality: coverage is currently complete for Catalonia's internal basins and is being extended progressively to the other river basin districts and to the Valencian Community. Each data point states its coverage.
- Aguaindex does not replace land registry or cadastral information, nor does it certify compliance with any legal obligation.
- The result depends on how precisely the address or cadastral reference can be located.
Regulatory framework
SNCZI mapping is produced under Directive 2007/60/EC and Royal Decree 903/2010 on the assessment and management of flood risks. Aguaindex follows the draft royal decree on flood risk management as a regulatory reference; it is not used as a calculation source.
Changelog
- v0.1 · October 2026First public draft. Score bands, sources, location and limitations.