HydrionisGlobal Water Intelligence
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Hydrionis for media and journalism

Checkable figures with the source, the method and the date on the same screen, and a clear statement of what each number does not show — so a story stands up when someone challenges it.

Reporters, editors, fact-checkers, data desks425,869 relevant observations
425,869
Observations available
2
Relevant datasets
1836–2026
Period covered
2
Commercially reusable

What you can answer here

Was this the driest year on record?

England rainfall from 1836, with every year placeable against the full record and against the computed 1991–2020 normal.

Where it stops: On record means within the record held. The England and Wales precipitation series begins in 1766 and Hydrionis holds the HadUK-Grid series from 1836.

Go to the data →

Are the rivers getting worse?

Per-point nutrient and oxygen records for English rivers since 2000 — and an explicit statement that a national trend line drawn from them would partly measure which points were still being sampled.

Where it stops: The large improvement in English river chemistry predates 2000, when this archive begins. Hydrionis does not publish a national trend it cannot support.

Go to the data →

Relevant datasets

DatasetObservationsCoverageLicence
England River Water Quality Dataset252,8572000–2025Commercial use permitted
UK Historical Rainfall Dataset173,0121836–2026Commercial use permitted

Key measures

Full dictionary →
MeasureDefinitionUnit
Nitrate as nitrogenConcentration of nitrate in water expressed as the mass of nitrogen it contains, the convention used in environmental monitoring.
Reported as nitrogen, not as the nitrate ion: multiply by 4.43 to compare with a drinking-water standard written as NO₃. Concentrations are specific to the sampling point and vary strongly with river flow, so a wet year and a dry year are not directly comparable.
mg/l as N
Orthophosphate as phosphorusConcentration of reactive orthophosphate expressed as the mass of phosphorus it contains.
Reported as phosphorus, not as the phosphate ion: multiply by 3.07 to express as PO₄. Reactive orthophosphate is a smaller quantity than total phosphorus, so the two must not be compared.
mg/l as P
Annual precipitationTotal depth of precipitation falling over a defined area in a calendar or water year.
Annual totals for different countries are not comparable as a measure of water availability. A large arid country and a small wet one can have similar national average rainfall while having entirely different renewable water resources per person. Gauge networks also differ in density, and mountain precipitation is systematically under-measured.
mm

What Hydrionis does not hold for you

Access

Everything referenced here is available through the JSON API and, where the source licence permits redistribution, as CSV extracts. Field definitions are in the data dictionary.

For bulk extracts, higher-volume API access, commercial licensing or bespoke work, see data enquiries.

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