Root causes · updated 30 Oct 2026
Threats to water access and health: a causal tree
Eleven threats to safe, accessible water, traced through their direct causes and the causes behind those, down to eight root drivers. The drivers are ranked by how many of the eleven threats they feed.
The links are qualitative summaries drawn from WHO, EEA, IPCC, UNEP and RIVM material. No figures are implied.
Recurring root drivers
How many of the 11 threats each driver feeds; ties broken by number of causal links.
Governance, regulation and enforcement gaps
11 of 11 · 19 links
Economic incentives that leave pollution and depletion unpriced
9 of 11 · 20 links
Underinvestment and short-term public finance
9 of 11 · 16 links
Power imbalances and inequality
9 of 11 · 16 links
Knowledge, monitoring and data gaps
9 of 11 · 14 links
Population growth and urbanisation
8 of 11 · 11 links
Climate change
7 of 11 · 10 links
Consumption patterns (diets, products, lifestyles)
5 of 11 · 5 links
What this means for a chapter
Governance gaps and unpriced incentives sit under almost every threat. So the most leverage comes from monitoring, transparency, polluter-pays and enforcement, not from fixing one contaminant at a time. That is what a chapter does:
- → Measure and publish. Data gaps feed 9 of 11 threats. Chapters publish well-depth, flow and water-quality data so problems show up early and nobody argues from guesses.
- → Put the cost in the compact. Unpriced incentives feed 9 of 11 threats. A watershed compact writes replenishment targets and infrastructure capital into a signed agreement, so depletion is no longer free.
- → Make it enforceable. Governance gaps feed 11 of 11 threats. A legally binding compact gives residents and farmers something concrete to hold every party to.
Where drivers meet threats
A dot means the driver sits under at least one cause of that threat. Select a number to open the threat.
| Root driver | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | Fed |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Governance, regulation and enforcement gaps | yes | yes | yes | yes | yes | yes | yes | yes | yes | yes | yes | 11/11 |
| Economic incentives that leave pollution and depletion unpriced | yes | yes | yes | yes | yes | yes | yes | yes | no | yes | no | 9/11 |
| Underinvestment and short-term public finance | yes | yes | yes | yes | no | yes | yes | yes | yes | no | yes | 9/11 |
| Power imbalances and inequality | yes | yes | yes | yes | yes | no | no | yes | yes | yes | yes | 9/11 |
| Knowledge, monitoring and data gaps | yes | yes | no | yes | yes | yes | yes | yes | yes | yes | no | 9/11 |
| Population growth and urbanisation | yes | yes | yes | no | yes | yes | yes | no | yes | no | yes | 8/11 |
| Climate change | yes | no | no | no | yes | yes | yes | yes | no | yes | yes | 7/11 |
| Consumption patterns (diets, products, lifestyles) | yes | yes | yes | no | no | no | yes | no | no | yes | no | 5/11 |
1 Microbial contamination · 2 Chemical contamination (PFAS, pharmaceuticals, pesticides) · 3 Nitrate and nutrient pollution · 4 Heavy metals and natural toxins (arsenic, lead) · 5 Scarcity and over-abstraction · 6 Salinisation · 7 Drought and floods · 8 Infrastructure failure and leakage · 9 Unaffordability and inequitable access · 10 Ecosystem degradation · 11 Conflict and disputes over water
The eleven threats
Open a threat to see its direct causes, the causes behind them, and the root drivers underneath.
1 Microbial contamination Pathogens from faeces in drinking-water sources and supply.
Direct causes → underlying causes → root drivers
Untreated or poorly treated sewage
Missing or overloaded treatment plants
UnderinvestmentPopulation & cities
Sanitation not prioritised in budgets
Power & inequalityGovernance gaps
Combined sewer overflows after heavy rain
Old combined sewer design
Underinvestment
More intense rainfall
Climate change
Livestock manure runoff
Intensive livestock concentrated near water
Unpriced incentivesConsumption
Weak buffer-zone rules
Governance gaps
Contamination in networks and storage
Pressure loss and intermittent supply
Underinvestment
Little routine water-quality testing
Data gapsUnderinvestment
Source: WHO fact sheet: Drinking-water
6 sources on the watch list face this →2 Chemical contamination (PFAS, pharmaceuticals, pesticides) Persistent and emerging chemicals in surface water and groundwater.
Direct causes → underlying causes → root drivers
Industrial discharges and legacy sites
Permits written before risks were known
Data gapsGovernance gaps
Clean-up costs not borne by polluters
Unpriced incentivesPower & inequality
Persistent chemicals in consumer products
Substance-by-substance regulation lags production
Governance gapsData gaps
Demand for cheap functional materials
ConsumptionUnpriced incentives
Pharmaceutical residues via wastewater
Most treatment plants not built to remove them
UnderinvestmentData gaps
Rising medicine use in ageing populations
Population & cities
Pesticide runoff and leaching
Farm economics reward high input use
Unpriced incentivesPower & inequality
Limited monitoring of metabolites
Data gaps
Source: RIVM: PFAS
27 sources on the watch list face this →3 Nitrate and nutrient pollution Excess nitrogen and phosphorus in groundwater and surface water.
Direct causes → underlying causes → root drivers
Fertiliser surplus on farmland
Subsidies and prices favour output over efficiency
Unpriced incentivesGovernance gaps
Demand for cheap meat and dairy
Consumption
Manure surpluses in livestock regions
Herd sizes exceed local land to absorb manure
Unpriced incentivesPower & inequality
Derogations and weak enforcement
Governance gaps
Urban wastewater nutrients
Incomplete nutrient removal at plants
Underinvestment
Growing urban loads
Population & cities
Source: EEA indicator: Nutrients in freshwater in Europe
23 sources on the watch list face this →4 Heavy metals and natural toxins (arsenic, lead) Toxic elements from geology, mining and old pipes.
Direct causes → underlying causes → root drivers
Lead service lines and fittings
Replacement repeatedly deferred
UnderinvestmentGovernance gaps
Lead pipes not mapped
Data gaps
Mining and smelting waste
Tailings liabilities externalised
Unpriced incentivesPower & inequality
Weak permitting and closure rules
Governance gaps
Geogenic arsenic or fluoride in wells
Wells drilled without testing
Data gapsUnderinvestment
No safe alternative source for poor households
Power & inequalityUnderinvestment
Source: WHO fact sheet: Arsenic
7 sources on the watch list face this →5 Scarcity and over-abstraction Use outpaces renewable supply; aquifers and rivers decline.
Direct causes → underlying causes → root drivers
Groundwater pumping for irrigation
Cheap or free energy and water for pumping
Unpriced incentivesGovernance gaps
Unregistered wells and unmetered use
Governance gapsData gaps
Growing urban and industrial demand
Urban growth in water-stressed basins
Population & cities
Water-intensive industries sited without limits
Unpriced incentivesPower & inequality
Over-allocated water rights
Allocations set in wetter decades
Climate changeData gaps
Powerful users resist cuts
Power & inequality
Lower recharge and runoff
Changing rainfall and higher evaporation
Climate change
Sealed surfaces and drained wetlands
Population & citiesUnpriced incentives
Source: IPCC AR6 WGII Chapter 4: Water
28 sources on the watch list face this →6 Salinisation Salt intrusion into aquifers, rivers and intake points.
Direct causes → underlying causes → root drivers
Seawater intrusion into coastal aquifers
Over-pumping near coasts
Unpriced incentivesGovernance gaps
Sea-level rise
Climate change
Low river discharge lets the salt wedge move inland
Drier summers
Climate change
Upstream abstraction
Governance gapsPopulation & cities
Irrigation salinity and drainage
Poor drainage design
Data gapsUnderinvestment
Land subsidence in drained peat and deltas
Drainage for agriculture and building
Unpriced incentivesPopulation & cities
Source: EEA: Europe's state of water 2024
12 sources on the watch list face this →7 Drought and floods Too little or too much water, both damaging supply and quality.
Direct causes → underlying causes → root drivers
More frequent and severe extremes
Greenhouse gas emissions
Climate changeConsumptionUnpriced incentives
Floodplain and catchment development
Land-value pressure to build in risk zones
Unpriced incentivesPopulation & cities
Spatial planning ignores water
Governance gaps
Loss of natural buffers (wetlands, soils, forest)
Conversion to farmland and housing
Unpriced incentivesPopulation & cities
Weak preparedness and early warning
Plans and data not updated
Data gapsUnderinvestment
Source: WHO fact sheet: Drought
40 sources on the watch list face this →8 Infrastructure failure and leakage Ageing pipes, plants and dams lose water and fail.
Direct causes → underlying causes → root drivers
Ageing assets beyond design life
Renewal deferred to keep tariffs low
UnderinvestmentPower & inequality
No asset inventory or condition data
Data gaps
Non-revenue water (leaks, illegal connections)
Weak utility management incentives
Governance gapsUnpriced incentives
Shortage of skilled operators
Low pay and training budgets
Underinvestment
Climate stress on assets
Heat, floods and ground movement
Climate change
Source: WHO fact sheet: Drinking-water
9 Unaffordability and inequitable access People near water still cannot get safe water they can pay for.
Direct causes → underlying causes → root drivers
Informal settlements left off networks
Tenure rules block service
Governance gapsPower & inequality
Rapid unplanned urban growth
Population & cities
Tariffs high relative to poor households' income
Full cost recovery without social tariffs
UnderinvestmentGovernance gaps
Income inequality
Power & inequality
Rural and marginalised groups underserved
Investment follows political influence
Power & inequalityUnderinvestment
Users not counted in data
Data gaps
Source: WHO fact sheet: Sanitation
10 Ecosystem degradation Rivers, wetlands and catchments lose the functions that clean and store water.
Direct causes → underlying causes → root drivers
Wetland drainage and river channelisation
Land conversion pays more than conservation
Unpriced incentives
Nature's water services unvalued
Data gapsUnpriced incentives
Dams and barriers fragment rivers
Energy and irrigation priorities
Unpriced incentivesPower & inequality
Deforestation and soil erosion in catchments
Commodity demand
ConsumptionUnpriced incentives
Weak land-use enforcement
Governance gaps
Warming and low flows
Climate change
Climate change
Source: UNEP: Fresh water
12 sources on the watch list face this →11 Conflict and disputes over water Water as a source, target or casualty of conflict.
Direct causes → underlying causes → root drivers
Competition in shared basins
No or weak transboundary agreements
Governance gapsPower & inequality
Rising demand and lower flows
Population & citiesClimate change
Attacks on and neglect of water systems in war
Armed conflict and state fragility
Power & inequalityGovernance gaps
Displacement overwhelming host supplies
Conflict and climate-related displacement
Climate changePower & inequality
No emergency finance
Underinvestment
Source: IPCC AR6 WGII Chapter 4: Water
Sources
- WHO fact sheet: Drinking-water (who.int)
- WHO fact sheet: Sanitation (who.int)
- WHO fact sheet: Arsenic (who.int)
- WHO fact sheet: Drought (who.int)
- RIVM: PFAS (rivm.nl)
- EEA indicator: Nutrients in freshwater in Europe (eea.europa.eu)
- EEA: Europe's state of water 2024 (eea.europa.eu)
- IPCC AR6 WGII Chapter 4: Water (ipcc.ch)
- UNEP: Fresh water (unep.org)
See it on the ground
The watch list shows 76 drinking-water sources where these threats are documented, from Dutch dune catchments to aquifers worldwide.
Open the watch list