Data dictionary | Hydrionis

drinking-water

Identifier	Definition	Unit	Held
`drinking-water-compliance-micro` Drinking water microbiological compliance	Percentage of regulatory drinking-water samples in a supply that met every microbiological limit. Comparability: Compliance is computed over the samples a supplier was required to take, and sampling frequency scales with population served. A small supply taking twelve samples a year and a city taking twelve thousand can both report 100%, and one failure moves the small supply far further. Compliance percentages are not comparable between supplies of very different size, and not comparable between countries whose sampling regimes and parameter sets differ.	% Spatially aggregated	1,072 2008–2019 98 subjects year
`drinking-water-compliance-physchem` Drinking water physico-chemical compliance	Percentage of regulatory drinking-water samples in a supply that met every physico-chemical limit. Comparability: The parameter set behind a physico-chemical compliance figure differs between regulatory regimes, so the same percentage does not represent the same test in two countries. Within one regime, sampling frequency scales with population served, so small and large supplies are not directly comparable.	% Spatially aggregated	1,072 2008–2019 98 subjects year
`drinking-water-sample-count` Drinking water samples analysed	Number of regulatory drinking-water sample results held for a supply area over a period. Comparability: A count of results Hydrionis holds, which is the count the publisher exposed through its API. It is not a statement about how many samples a supplier was legally required to take.	samples Spatially aggregated	404 2022–2025 101 subjects year
`dw-nitrate-concentration` Nitrate in drinking water	Mean concentration of nitrate, expressed as the nitrate ion in treated drinking water, computed over quantified samples only. Comparability: A mean over quantified samples only. Where most samples are censored this describes the detectable minority, not the supply. Not comparable with a mean computed by substituting zero or half the detection limit for censored results, which is the more common convention elsewhere.	mg/l as NO₃ Spatially aggregated	404 2022–2025 101 subjects year
`dw-nitrate-quantified` Nitrate quantified sample share	Percentage of drinking-water samples analysed for nitrate, expressed as the nitrate ion that returned a numeric result rather than a result below the detection limit. Comparability: Depends on the detection limit laboratories achieved, which improves over time. A rise can mean more of the substance is present or that it became visible at lower concentrations, and the two cannot be separated from this series alone.	% Spatially aggregated	404 2022–2025 101 subjects year
`dw-nitrate-exceedance` Nitrate limit exceedance rate	Percentage of drinking-water samples analysed for nitrate, expressed as the nitrate ion whose result exceeded the regulatory limit of 50 mg/l as NO₃. Comparability: Computed against the French regulatory limit of 50 mg/l as NO₃. Limits for the same substance differ between jurisdictions, so exceedance rates are not comparable internationally without checking both standards.	% Spatially aggregated	404 2022–2025 101 subjects year
`dw-arsenic-quantified` Arsenic quantified sample share	Percentage of drinking-water samples analysed for arsenic that returned a numeric result rather than a result below the detection limit. Comparability: Depends on the detection limit laboratories achieved, which improves over time. A rise can mean more of the substance is present or that it became visible at lower concentrations, and the two cannot be separated from this series alone.	% Spatially aggregated	398 2022–2025 100 subjects year
`dw-arsenic-exceedance` Arsenic limit exceedance rate	Percentage of drinking-water samples analysed for arsenic whose result exceeded the regulatory limit of 10 µg/l. Comparability: Computed against the French regulatory limit of 10 µg/l. Limits for the same substance differ between jurisdictions, so exceedance rates are not comparable internationally without checking both standards.	% Spatially aggregated	398 2022–2025 100 subjects year
`dw-pesticides-total-quantified` Total pesticides quantified sample share	Percentage of drinking-water samples analysed for the sum of the pesticides analysed that returned a numeric result rather than a result below the detection limit. Comparability: Depends on the detection limit laboratories achieved, which improves over time. A rise can mean more of the substance is present or that it became visible at lower concentrations, and the two cannot be separated from this series alone.	% Spatially aggregated	397 2022–2025 100 subjects year
`dw-pesticides-total-exceedance` Total pesticides limit exceedance rate	Percentage of drinking-water samples analysed for the sum of the pesticides analysed whose result exceeded the regulatory limit of 0.5 µg/l. Comparability: Computed against the French regulatory limit of 0.5 µg/l. Limits for the same substance differ between jurisdictions, so exceedance rates are not comparable internationally without checking both standards.	% Spatially aggregated	397 2022–2025 100 subjects year
`dw-pesticides-total-concentration` Total pesticides in drinking water	Mean concentration of the sum of the pesticides analysed in treated drinking water, computed over quantified samples only. Comparability: A mean over quantified samples only. Where most samples are censored this describes the detectable minority, not the supply. Not comparable with a mean computed by substituting zero or half the detection limit for censored results, which is the more common convention elsewhere.	µg/l Spatially aggregated	392 2022–2025 98 subjects year
`dw-arsenic-concentration` Arsenic in drinking water	Mean concentration of arsenic in treated drinking water, computed over quantified samples only. Comparability: A mean over quantified samples only. Where most samples are censored this describes the detectable minority, not the supply. Not comparable with a mean computed by substituting zero or half the detection limit for censored results, which is the more common convention elsewhere.	µg/l Spatially aggregated	352 2022–2025 94 subjects year
`dw-lead-quantified` Lead quantified sample share	Percentage of drinking-water samples analysed for lead that returned a numeric result rather than a result below the detection limit. Comparability: Depends on the detection limit laboratories achieved, which improves over time. A rise can mean more of the substance is present or that it became visible at lower concentrations, and the two cannot be separated from this series alone.	% Spatially aggregated	228 2022–2025 70 subjects year
`dw-lead-exceedance` Lead limit exceedance rate	Percentage of drinking-water samples analysed for lead whose result exceeded the regulatory limit of 10 µg/l. Comparability: Computed against the French regulatory limit of 10 µg/l. Limits for the same substance differ between jurisdictions, so exceedance rates are not comparable internationally without checking both standards.	% Spatially aggregated	228 2022–2025 70 subjects year
`dw-lead-concentration` Lead in drinking water	Mean concentration of lead in treated drinking water, computed over quantified samples only. Comparability: A mean over quantified samples only. Where most samples are censored this describes the detectable minority, not the supply. Not comparable with a mean computed by substituting zero or half the detection limit for censored results, which is the more common convention elsewhere.	µg/l Spatially aggregated	222 2022–2025 69 subjects year
`dw-pfos-quantified` PFOS quantified sample share	Percentage of drinking-water samples analysed for perfluorooctane sulfonic acid that returned a numeric result rather than a result below the detection limit. Comparability: Depends on the detection limit laboratories achieved, which improves over time. A rise can mean more of the substance is present or that it became visible at lower concentrations, and the two cannot be separated from this series alone.	% Spatially aggregated	117 2022–2025 94 subjects year
`dw-pfos-concentration` PFOS in drinking water	Mean concentration of perfluorooctane sulfonic acid in treated drinking water, computed over quantified samples only. Comparability: A mean over quantified samples only. Where most samples are censored this describes the detectable minority, not the supply. Not comparable with a mean computed by substituting zero or half the detection limit for censored results, which is the more common convention elsewhere.	µg/l Spatially aggregated	110 2022–2025 88 subjects year

abstraction

Identifier	Definition	Unit	Held
`abstraction-volume-public-supply` Water abstracted for public water supply	Abstraction for treatment and distribution as drinking water through a public supply network. Comparability: Reported abstraction for a declared purpose, not consumption. Purpose categories are defined by the reporting jurisdiction and do not map exactly onto categories used elsewhere, so a single purpose should not be compared across countries without checking both definitions. Not to be confused with: abstraction-volume-licensed	Mm³ Publisher unit: m³ Spatially aggregated, Reported	2,496 1970–2024 139 subjects year
`abstraction-volume-total` Water abstracted, all purposes	Total volume of water reported as actually abstracted from surface water and groundwater in a year, across all declared purposes. Comparability: Reported abstraction, not licensed entitlement and not consumption. Water abstracted is largely returned to the environment after use; the share consumed is a different and much smaller quantity. Coverage depends on which abstractors are required to declare, so a national total is a total of what is declared rather than of what is taken. Not to be confused with: water-withdrawal-total, abstraction-volume-licensed	Mm³ Publisher unit: m³ Spatially aggregated, Calculated, Reported	2,422 1970–2024 139 subjects multi-year, year
`abstraction-volume-industry` Water abstracted for industry	Abstraction for industrial and economic activity other than irrigation and electricity generation. Comparability: Reported abstraction for a declared purpose, not consumption. Purpose categories are defined by the reporting jurisdiction and do not map exactly onto categories used elsewhere, so a single purpose should not be compared across countries without checking both definitions. Not to be confused with: abstraction-volume-licensed	Mm³ Publisher unit: m³ Spatially aggregated, Reported	2,256 1970–2024 136 subjects year
`abstraction-volume-irrigation` Water abstracted for irrigation and agriculture	Abstraction for crop irrigation and other agricultural use. Comparability: Reported abstraction for a declared purpose, not consumption. Purpose categories are defined by the reporting jurisdiction and do not map exactly onto categories used elsewhere, so a single purpose should not be compared across countries without checking both definitions. Not to be confused with: abstraction-volume-licensed	Mm³ Publisher unit: m³ Spatially aggregated, Reported	2,050 1970–2024 130 subjects year
`abstraction-volume-groundwater` Water abstracted from fresh groundwater	Abstraction from aquifers, through wells and boreholes. Comparability: A component of total abstraction by the kind of water body it came from, not by what it was used for. Surface and groundwater are reported separately by the publisher and are not derived from one another here. Not to be confused with: abstraction-volume-licensed	Mm³ Calculated, Reported	972 1970–2024 36 subjects multi-year, year
`abstraction-volume-energy` Water abstracted for electricity generation	Abstraction for cooling and operation of electricity generating plant. Comparability: Reported abstraction for a declared purpose, not consumption. Purpose categories are defined by the reporting jurisdiction and do not map exactly onto categories used elsewhere, so a single purpose should not be compared across countries without checking both definitions. Not to be confused with: abstraction-volume-licensed	Mm³ Publisher unit: m³ Spatially aggregated, Reported	970 1970–2024 71 subjects year
`abstraction-volume-surface` Water abstracted from fresh surface water	Abstraction from rivers, lakes and reservoirs. Comparability: A component of total abstraction by the kind of water body it came from, not by what it was used for. Surface and groundwater are reported separately by the publisher and are not derived from one another here. Not to be confused with: abstraction-volume-licensed	Mm³ Calculated, Reported	919 1970–2024 36 subjects multi-year, year
`abstraction-volume-canals` Water abstracted for canals and navigation	Abstraction to maintain water levels in canals and navigations. Comparability: Reported abstraction for a declared purpose, not consumption. Purpose categories are defined by the reporting jurisdiction and do not map exactly onto categories used elsewhere, so a single purpose should not be compared across countries without checking both definitions. Not to be confused with: abstraction-volume-licensed	Mm³ Publisher unit: m³ Spatially aggregated	715 2008–2023 55 subjects year
`abstraction-volume-net` Net freshwater abstraction	Total gross abstraction less water returned to the environment without having been used. Comparability: Not consumption. The difference between gross and net abstraction is water returned without use; the difference between net abstraction and consumption is water returned after use, which is far larger and is not reported here. Not to be confused with: abstraction-volume-total, water-withdrawal-total	Mm³ Calculated, Reported	596 1970–2024 33 subjects multi-year, year
`abstraction-volume-mining` Water abstracted for mining and quarrying	Abstraction for mineral extraction, including dewatering of workings. Comparability: Reported abstraction for a declared purpose, not consumption. Purpose categories are defined by the reporting jurisdiction and do not map exactly onto categories used elsewhere, so a single purpose should not be compared across countries without checking both definitions. Not to be confused with: abstraction-volume-licensed	Mm³ Reported	565 1970–2024 32 subjects year
`abstraction-volume-services` Water abstracted for services	Abstraction by the service sector — commercial premises, hospitality, offices and public buildings — where it is taken directly rather than bought from a public supply. Comparability: Reported abstraction for a declared purpose, not consumption. Purpose categories are defined by the reporting jurisdiction and do not map exactly onto categories used elsewhere, so a single purpose should not be compared across countries without checking both definitions. Not to be confused with: abstraction-volume-licensed	Mm³ Reported	492 1980–2024 28 subjects year
`water-returned-without-use` Water returned without use	Water abstracted and returned to the environment without having been used for any purpose. Comparability: Reported by some countries and not by others, so an absent value means "not reported" rather than zero. Comparing gross abstraction across a country that reports this and one that does not compares two different quantities.	Mm³ Calculated, Reported	362 1980–2024 23 subjects multi-year, year
`abstraction-volume-aquaculture` Water abstracted for aquaculture	Abstraction for fish farming and other aquaculture. Comparability: Reported abstraction for a declared purpose, not consumption. Purpose categories are defined by the reporting jurisdiction and do not map exactly onto categories used elsewhere, so a single purpose should not be compared across countries without checking both definitions. Not to be confused with: abstraction-volume-licensed	Mm³ Reported	329 1990–2024 21 subjects year
`abstraction-volume-households` Water abstracted for private households	Abstraction by households from their own source, typically a private well or borehole. Comparability: Reported abstraction for a declared purpose, not consumption. Purpose categories are defined by the reporting jurisdiction and do not map exactly onto categories used elsewhere, so a single purpose should not be compared across countries without checking both definitions. Not to be confused with: abstraction-volume-licensed	Mm³ Reported	234 1970–2024 17 subjects year

sector-use

Identifier	Definition	Unit	Held
`facility-water-withdrawal` Facility water withdrawal	Volume of water a single facility took from its source in a reporting period, before any return. Comparability: A facility figure, never a company total. Two plants with the same generation can differ a hundredfold in withdrawal purely by cooling design, so withdrawal ranks cooling technology at least as much as it ranks water use. Not to be confused with: facility-water-consumption, abstraction-volume-total	Mm³ Publisher unit: million US gallons Spatially aggregated	7,414 2014–2024 834 subjects year
`facility-water-consumption` Facility water consumption	Volume of water a single facility withdrew and did not return to the water environment. Comparability: Consumption and withdrawal are not alternative measurements of one quantity and must never be substituted for one another. A facility ranked highest on withdrawal is frequently well down the consumption ranking, and the reverse. Not to be confused with: facility-water-withdrawal	Mm³ Publisher unit: million US gallons Spatially aggregated	6,943 2014–2024 813 subjects year
`withdrawal-agriculture-share` Agricultural share of withdrawal	Percentage of total freshwater withdrawal used by agriculture. Comparability: A high agricultural share reflects the size and irrigation intensity of the farming sector rather than inefficiency. Countries at the top of any such ranking are typically food producers in arid regions.	% Calculated, Reported	6,138 1965–2022 180 subjects multi-year, year
`withdrawal-municipal-share` Municipal share of withdrawal	Percentage of total freshwater withdrawal supplied through public water systems. Comparability: The municipal share rises where agriculture and industry are small, so a high figure often indicates a service-based economy rather than high household consumption.	% Calculated, Reported	6,102 1965–2022 179 subjects multi-year, year
`withdrawal-industry-share` Industrial share of withdrawal	Percentage of total freshwater withdrawal used by industry, including energy cooling. Comparability: Countries differ in whether thermoelectric cooling is counted as industrial withdrawal. Where it is included, the industrial share can exceed 50% in countries with large freshwater-cooled power fleets, which reflects cooling arrangements rather than manufacturing intensity.	% Calculated, Reported	6,001 1965–2022 179 subjects multi-year, year
`facility-water-reclaimed` Facility reclaimed water use	Volume a facility took from reclaimed or reused sources rather than from fresh surface water or groundwater. Comparability: A component of withdrawal identified by its source, not an additional volume. Adding it to withdrawal would double-count it. Not to be confused with: facility-water-withdrawal	Mm³ Publisher unit: million US gallons Spatially aggregated	611 2014–2024 69 subjects year
`household-consumption-per-capita` Household water use per person	Average volume of water used per person per day in the home. Comparability: Definitions differ on whether supply pipe losses, garden use and non-household use on domestic meters are included. Metered and unmetered households also differ substantially, so a national average masks a wide distribution.	l/person/day Reported	36 2023–2024 18 subjects year

utility-performance

Identifier	Definition	Unit	Held
`water-services-reporting` Water services reporting	Number of water services that made a statutory performance return for an area in a given year. Comparability: A count of services that reported, not of services that exist. Reporting is voluntary in practice and varies by year, so a fall in this count is a fall in coverage rather than in the number of water services.	services Spatially aggregated	1,154 2008–2019 102 subjects year
`network-efficiency` Distribution network efficiency	Volume billed or otherwise accounted for as a percentage of the volume put into distribution. Comparability: A French regulatory indicator (P104.3). It is not the inverse of the English leakage measures and must not be converted into them: England and Wales report leakage as a volume per day and per property, computed from a night-flow water balance under different rules. Comparing a rendement with a litres-per-property-per-day figure compares two different calculations. Not to be confused with: leakage-volume, leakage-per-property	% Spatially aggregated	1,076 2008–2019 98 subjects year
`supply-interruption-rate` Unplanned supply interruption rate	Number of unplanned interruptions to water supply per thousand connected subscribers in a year. Comparability: Counts events per thousand subscribers. The English and Welsh measure of the same concept reports the average duration of interruption per property instead, so the two rank utilities differently and cannot be compared or converted. Not to be confused with: supply-interruptions	per 1,000 subscribers/yr Spatially aggregated	651 2008–2019 93 subjects year
`distribution-input-per-capita` Distribution input per person	Total water put into the distribution system divided by the population served, per person per day. Comparability: A high figure can mean high consumption, high leakage or a large non-household base, and the three cannot be told apart from this number alone. Read it alongside per-capita consumption and leakage rather than as a demand measure. Not to be confused with: household-consumption-per-capita	l/person/day Reported	36 2023–2024 18 subjects year
`household-metering` Household metering	Share of household customers billed on a measured rather than an unmeasured tariff. Comparability: Metering share is a policy and regulatory outcome as much as an operational one — companies in water-stressed areas have been permitted compulsory metering that others have not — so it ranks circumstances rather than performance.	% Reported	36 2023–2024 18 subjects year
`non-household-metering` Non-household metering	Share of non-household customers billed on a measured tariff, excluding void properties. Comparability: Reported excluding voids — properties connected but unoccupied — so it is not comparable with a figure that includes them. The exclusion is stated because including voids depresses the percentage by several points.	% Reported	36 2023–2024 18 subjects year

quality

Identifier	Definition	Unit	Held
`nitrate-as-n` Nitrate as nitrogen	Concentration of nitrate in water expressed as the mass of nitrogen it contains, the convention used in environmental monitoring. Comparability: 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. Not to be confused with: nitrate	mg/l as N Publisher unit: MILLIGRAM PER LITRE Spatially aggregated, Calculated	57,328 2000–2025 3,923 subjects multi-year, year
`dissolved-oxygen` Dissolved oxygen	The concentration of oxygen dissolved in water, essential for aquatic life. Comparability: Oxygen solubility falls as temperature and salinity rise, so an absolute concentration must be read alongside temperature. Percentage saturation is often the more meaningful figure.	mg/l Publisher unit: MILLIGRAM PER LITRE Spatially aggregated, Calculated	49,552 2000–2025 3,679 subjects multi-year, year
`dissolved-oxygen-saturation` Dissolved oxygen saturation	Dissolved oxygen expressed as a percentage of the maximum the water could hold at its temperature and pressure. Comparability: Saturation above 100% is not better than 100%. Strong daytime over-saturation and severe night-time depletion frequently occur in the same enriched river, and a daytime spot sample will not show the depletion.	% Publisher unit: PERCENT Spatially aggregated, Calculated	30,949 2000–2025 2,365 subjects multi-year, year
`orthophosphate-as-p` Orthophosphate as phosphorus	Concentration of reactive orthophosphate expressed as the mass of phosphorus it contains. Comparability: 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. Not to be confused with: phosphate	mg/l as P Publisher unit: MILLIGRAM PER LITRE Spatially aggregated, Calculated	25,038 2000–2025 1,899 subjects multi-year, year
`ammoniacal-nitrogen` Ammoniacal nitrogen	Combined concentration of ammonia and ammonium expressed as the mass of nitrogen, a standard indicator of recent organic or sewage pollution. Comparability: Reported as nitrogen rather than as the ammonium ion. The proportion present as toxic un-ionised ammonia rises sharply with pH and temperature, so the same concentration is not equally harmful in different rivers. Not to be confused with: ammonium	mg/l as N Publisher unit: MILLIGRAM PER LITRE Spatially aggregated, Calculated	20,772 2000–2025 1,565 subjects multi-year, year

temperature

Identifier	Definition	Unit	Held
`temperature-mean-monthly` Mean monthly air temperature	Average near-surface air temperature over a calendar month. Comparability: Strongly seasonal. Compare a month against the same month in other years, never against an adjacent month. Included because temperature drives evaporative demand and water demand, not as general climate reporting.	°C Spatially aggregated	29,087 1884–2026 17 subjects month
`temperature-max-monthly` Mean monthly maximum temperature	Average of daily maximum near-surface air temperatures over a calendar month. Comparability: A mean of daily maxima, not the highest temperature recorded in the month. The two are frequently confused and differ substantially.	°C Spatially aggregated	29,087 1884–2026 17 subjects month
`temperature-min-monthly` Mean monthly minimum temperature	Average of daily minimum near-surface air temperatures over a calendar month. Comparability: A mean of daily minima, not the lowest temperature recorded in the month.	°C Spatially aggregated	29,087 1884–2026 17 subjects month
`sunshine-monthly` Monthly sunshine duration	Total hours of bright sunshine recorded over a calendar month. Comparability: Held because solar radiation drives evaporation. The measurement basis changed from Campbell-Stokes recorders to electronic sensors over the record, which introduces a step that is not a climate signal.	hours Spatially aggregated	23,783 1910–2026 17 subjects month
`temperature-mean-annual` Mean annual air temperature	Average near-surface air temperature over a year. Comparability: Included because temperature drives evaporation, evapotranspiration and water demand, not as general climate reporting. Station siting and urban heat effects both influence local records.	°C Spatially aggregated, Calculated	2,652 1884–2025 17 subjects multi-year, normal, year

leakage

Identifier	Definition	Unit	Held
`linear-leakage-index` Linear leakage index	Volume lost from the distribution network per kilometre of main per day. Comparability: A French regulatory indicator (P106.3), normalised by network length. The English and Welsh leakage-per-property measure is normalised by connections instead, so the two rank networks differently and cannot be placed on one scale. Not to be confused with: leakage-per-property, leakage-volume	m³/km/day Spatially aggregated	1,070 2008–2019 98 subjects year
`leakage-per-person` Leakage per person	Leakage divided by the resident population the company supplies, expressed per person per day. Comparability: Normalising by population rather than by property shifts what the figure reflects: a company serving many small households will look worse per property and better per person than one serving few large ones. It is a different ranking of the same losses, not a better one. Not to be confused with: household-consumption-per-capita	l/person/day Reported	36 2023–2024 18 subjects year
`leakage-share-of-input` Leakage as a share of distribution input	Leakage expressed as a percentage of the water the company put into its distribution system. Comparability: A percentage of input falls when demand rises even if the losses themselves are unchanged, so it moves with consumption as well as with network condition. Compare a company against its own record before comparing it against another. Not to be confused with: non-revenue-water	% Reported	36 2023–2024 18 subjects year
`leakage-per-property` Leakage per property	Leakage divided by the number of connected properties. Comparability: Normalising by property makes utilities comparable in a way absolute leakage does not, but still reflects network density, pipe age, material, pressure and ground conditions rather than management quality alone.	l/property/day Reported	18 2024–2024 18 subjects year
`leakage-volume` Leakage	Water lost from the distribution network and from customer supply pipes through physical escape, expressed as a daily volume. Comparability: Absolute leakage scales with the size of the company, so it must not be used to rank utilities of different sizes. Use litres per property per day or leakage per kilometre of main for comparison. Not to be confused with: non-revenue-water	Ml/d Reported	13 2024–2024 13 subjects year

precipitation

Identifier	Definition	Unit	Held
`precipitation-monthly` Monthly precipitation	Total depth of precipitation falling over a defined area within a calendar month. Comparability: Monthly totals are dominated by seasonality. Compare a month against the same month in other years, or against the long-term average for that month, never against an adjacent month.	mm Spatially aggregated, Measured	156,845 1836–2026 375 subjects month
`precipitation-seasonal` Seasonal precipitation	Total depth of precipitation falling over a defined area within a meteorological season. Comparability: Meteorological seasons are fixed three-month blocks — winter is December to February, and its December belongs to the previous calendar year. Comparing a season across years is valid; comparing adjacent seasons is not.	mm Spatially aggregated	12,937 1836–2026 17 subjects season
`precipitation-annual` Annual precipitation	Total depth of precipitation falling over a defined area in a calendar or water year. Comparability: 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 Spatially aggregated, Calculated	3,553 1836–2025 17 subjects multi-year, normal, year

river-flow

Identifier	Definition	Unit	Held
`river-flow-mean` Mean river flow	Average volumetric discharge past a gauging station over a stated period. Comparability: Flow is a property of a specific gauge on a specific reach, and cannot be attributed to a river as a whole. Two gauges on the same river can differ by an order of magnitude. Where a station measures flow through a sluice, lock or pumping station — much of the Dutch network does — discharge is signed and a negative value means water moving in the reverse direction, which is a real operating state and not an error. Managed flow of that kind is not comparable with discharge at a natural gauging station, because it reflects operational decisions as well as hydrology.	m³/s Publisher unit: ft3/s, m3/s Spatially aggregated, Calculated, Measured	20,034,991 1847–2026 4,323 subjects day, multi-year, year
`river-flow-monthly-mean` Mean monthly river flow	Average volumetric discharge past a gauging station over a calendar month. Comparability: A gauge property, not a river property. Strongly seasonal, so compare a month against the same month in other years. Gauge records contain breaks where structures were rebuilt or ratings revised.	m³/s Publisher unit: L/s, m3/s Spatially aggregated, Calculated, Measured	1,062,815 1879–2026 1,557 subjects month, normal
`river-level` River level	Height of the water surface at a gauging station, measured against that station’s own zero point. Comparability: Level is measured against each station’s own zero point, which is set locally and is not a common datum. Two gauges reading 3 m are not at the same height, and a level is not a depth of water: it says where the surface sits relative to a reference, not how deep the river is. Read a level against that gauge’s own record, never against another gauge’s.	m Publisher unit: cm Spatially aggregated, Measured	134,724 2025–2026 2,390 subjects day

resources

Identifier	Definition	Unit	Held
`renewable-water-resources` Total renewable freshwater resources	The long-term average annual flow of rivers and recharge of groundwater generated by precipitation within a country, plus inflows from upstream countries. Comparability: Total renewable resources include water flowing in from other countries, so a downstream country’s figure may depend on upstream decisions it does not control. Internal renewable resources exclude those inflows and are the better measure of self-sufficiency.	km³/yr Publisher unit: billion m³ Calculated, Derived	11,298 1961–2022 183 subjects multi-year, year
`renewable-water-per-capita` Renewable freshwater per person	Total renewable freshwater resources divided by population. Comparability: A per-capita average conceals seasonal and regional distribution entirely. A country can be water-rich on this measure and still have cities that run short.	m³/person/yr Calculated	11,267 1961–2022 183 subjects multi-year, year
`water-stock` Water stock	The volume of water held in a given store at a point in time. Comparability: Global stock estimates carry substantial uncertainty and are not measurements. Groundwater in particular cannot be measured directly at planetary scale, and published compilations differ by tens of percent. Not to be confused with: renewable-water-resources	km³ Estimated	12 1974–1974 12 subjects multi-year

chemistry

Identifier	Definition	Unit	Held
`ph` pH	The negative logarithm of hydrogen ion activity, measuring how acidic or alkaline water is. Comparability: pH varies with temperature and with dissolved carbon dioxide, so a sample measured hours after collection may not reflect the source. Averaging pH values arithmetically is strictly incorrect, since the scale is logarithmic.	pH Publisher unit: PH UNITS Spatially aggregated, Calculated	71,698 2000–2025 4,629 subjects multi-year, year
`water-temperature` Water temperature	Temperature of the water body or supply at the point of measurement.	°C Measured	104 2026–2026 104 subjects day

access

Identifier	Definition	Unit	Held
`basic-water-service` At least basic drinking water service	Percentage of population using an improved source with a round trip collection time of 30 minutes or less. Comparability: Modelled from household surveys rather than counted. The basic service definition is considerably weaker than safely managed, so high basic coverage is compatible with much lower safely managed coverage.	% Calculated, Modelled	5,304 2000–2024 201 subjects multi-year, year
`safely-managed-water` Safely managed drinking water	Percentage of population using an improved drinking water source that is accessible on premises, available when needed, and free from faecal and priority chemical contamination. Comparability: This is the strictest rung of the JMP service ladder and requires all three criteria simultaneously. It is much more demanding than "improved source", and countries can score far lower on it than headline access statistics suggest.	% Calculated, Modelled	3,846 2000–2024 144 subjects multi-year, year

tariff

Identifier	Definition	Unit	Held
`water-service-price-all-in` All-in water and sanitation price per cubic metre	Total price of water and sanitation service per cubic metre, including all taxes and levies, at a standard reference consumption. Comparability: An all-in price including standing charges, taxes and the sanitation component, which is a different quantity from the volumetric-rate-only metric `water-price-per-m3`: the two differ by the whole of the fixed charge and must never be plotted on one axis. A unit price at a fixed reference consumption, not an average bill. It includes standing charges apportioned over the reference volume, so a household consuming less than the reference pays more per cubic metre than this figure. Not comparable with bills stated in another currency without an exchange-rate assumption Hydrionis does not make. Not to be confused with: average-household-bill, water-price-per-m3	€/m³ Spatially aggregated	1,071 2008–2019 99 subjects year
`average-household-bill` Average annual household water bill	Average combined water and wastewater charge paid by a household in a year, before inflation adjustment. Comparability: Bills are not comparable across countries without stating the currency, the year, whether wastewater is included, whether the household is metered, and what average consumption is assumed. Some countries fund water partly through general taxation, which does not appear in the bill at all.	currency/yr Reported	6 2020–2025 1 subjects year

groundwater

Identifier	Definition	Unit	Held
`groundwater-level` Groundwater level	Elevation of the water table or piezometric surface at a monitoring borehole. Comparability: Levels are specific to a borehole and its aquifer, and must be read against that borehole’s own historic range. Absolute elevations from different boreholes are not comparable.	m Publisher unit: mAOD Spatially aggregated, Calculated, Measured	480,794 1836–2026 1,095 subjects month, multi-year, normal, year

withdrawal

Identifier	Definition	Unit	Held
`water-withdrawal-total` Total freshwater withdrawal	The total volume of freshwater taken from rivers, lakes and aquifers for all uses in a year, before any of it is returned. Comparability: Reporting years differ between countries, often by a decade. Withdrawal figures also vary in whether they include desalinated water and reused wastewater. Not to be confused with: water-consumption-total	km³/yr Publisher unit: billion m³ Calculated, Reported	6,780 1962–2022 181 subjects multi-year, year

stress

Identifier	Definition	Unit	Held
`water-stress` Water stress	Freshwater withdrawal as a percentage of available renewable freshwater resources, after accounting for environmental flow requirements. Comparability: A national figure averages over basins that can be individually far more stressed. Values above 100% mean withdrawal exceeds renewable supply, which is only possible by depleting groundwater, desalinating, or importing water.	% Calculated, Modelled	6,672 1962–2022 178 subjects multi-year, year

sanitation

Identifier	Definition	Unit	Held
`safely-managed-sanitation` Safely managed sanitation	Percentage of population using improved sanitation facilities not shared with other households, where excreta are safely disposed of in situ or treated off site. Comparability: Modelled estimates, not measured counts. The definition requires excreta to be safely disposed of in situ or treated off site, which is far stricter than having a toilet.	% Calculated, Modelled	3,781 2000–2024 143 subjects multi-year, year

wastewater

Identifier	Definition	Unit	Held
`storm-overflow-spills` Storm overflow spill events	Number of discharge events from storm overflows recorded by event duration monitoring in a year. Comparability: Counts depend on how many overflows are monitored. Monitoring coverage in England rose from a small minority of overflows to near-complete over roughly seven years, so an increase in recorded spills over that period is partly an increase in measurement.	spills/yr Measured	5 2020–2024 1 subjects year

infrastructure

Identifier	Definition	Unit	Held
`mains-renewal-rate` Mains renewal rate	Percentage of the distribution network replaced or renewed in a year, averaged over a rolling five-year window. Comparability: A five-year rolling average by construction (French indicator P107.2), so it responds slowly and a single year of heavy investment will not move it far. Renewal rates are not comparable between networks of very different age and material.	% Spatially aggregated	1,043 2008–2019 97 subjects year

reservoir

Identifier	Definition	Unit	Held
`reservoir-storage-volume` Reservoir stored volume	Volume of water held in a reservoir at a given time. Comparability: Storage is strongly seasonal and is managed, not merely observed: an operator drawing a reservoir down for flood control produces the same reading as a drought would. A month should be compared with the same month in other years, and a fall in storage should not be read as a supply signal without knowing the operating rule.	Mm³ Publisher unit: acre-feet Spatially aggregated, Calculated	54,832 1914–2026 92 subjects month, normal

Defined but not yet populated

Hydrionis defines these fields and holds no values for them. They are listed because a catalogue that showed only what exists would imply the rest had never been considered.

Precipitation anomaly · Annual snowfall · Snow water equivalent · Potential evapotranspiration · Actual evapotranspiration · Soil moisture deficit · Annual runoff · Standardised Precipitation Index (12-month) · Q95 low flow · Annual maximum river flow · Reservoir storage · Reservoir capacity · Groundwater abstraction · Groundwater depletion rate · Total water consumption · Freshwater withdrawal per person · Return flow · Wastewater safely treated · Non-revenue water · Water supply interruptions · Pollution incidents · Storm overflow spill duration · Water price per cubic metre · Total hardness · Alkalinity · Total dissolved solids · Electrical conductivity · Turbidity · Salinity · Calcium · Magnesium · Sodium · Potassium · Bicarbonate · Chloride · Sulphate · Silica · Fluoride · Iron · Manganese · Nitrate · Nitrite · Phosphate · Ammonium · Lead · Arsenic · Copper · Zinc · Aluminium · Mercury · Cadmium · Chromium · Nickel · PFOS · PFOA · Total PFAS · Total trihalomethanes · Bromate · Chlorine residual · Escherichia coli · Total coliforms · Cryptosporidium · Desalination capacity · Desalination specific energy consumption · Wastewater treatment capacity · Treated wastewater reused · Dam height · Population served · Water main length · Product water footprint · Data centre water consumption · Data centre water withdrawal · Water usage effectiveness · Licensed abstraction volume

Using these fields

Field identifiers are stable and are what the API and the CSV extracts use. Each dataset lists the fields it carries. Geography and entity identifiers follow the same rule: they do not change once published.