Accuracy and corrections
What Hydrionis does to make its figures right, what it does when one turns out to be wrong, and what you should do before relying on any of them for a decision that matters.
What this page does not say
It does not say the data is accurate. Hydrionis cannot know that about somebody else’s measurements, and a platform that claimed it would be making a promise it has no mechanism to keep. What it can say is what it actually does — validate, check, document, correct, withdraw, and keep a record of every change — and what a reader has to do before a decision with consequences. That is a weaker-sounding position and a considerably stronger one, because it is a position that can be kept.
What is actually checked
The checks that run before anything is published
- Every value resolves to a source. There is no second, looser path for a figure somebody knows to be true. A value without a source identifier is refused before it can be published, and nothing is published until every value has one.
- Every value is range-checked against its own metric. Metrics declare a plausible range, and a value outside it is refused rather than stored with a note. A catchment area that implies more runoff than any catchment produces means the published area and the published flow cannot both describe the same place, so no runoff is derived for that gauge at all.
- Units are converted once, at collection, and the publisher’s own value and unit are kept beside the converted one. A conversion applied twice is invisible in the result and obvious in the record.
- Derived values carry the identifier of every input. Any computed figure can be recomputed and checked, and its rights resolve from the inputs rather than from a convenient default.
- The whole estate is re-audited every time it is published. Routes, internal links, accessibility, rendered output, crawl cost, public wording and internal consistency each have a gate that stops publication rather than filing a warning.
What happens when something is wrong
A corrected value is a new observation that carries the identifier of the one it replaces. The superseded record is not deleted and stays queryable, so a figure quoted from Hydrionis last year can still be found even after the publisher revised it. That is the whole purpose of the Vault, which records 2,438 revised series alongside the values they replaced.
Where an error cannot be corrected — because the underlying source is wrong and has not been revised, or because Hydrionis cannot establish what the right value is — the affected information is withdrawn rather than left standing with a caveat. What each collection run refused to store, and why, is published on the data collection page.
Where Hydrionis shows nothing at all
A great deal of what makes the rest of this page true is the decision not to publish. Where a value cannot be defended, Hydrionis withholds it rather than estimating one — and the reasoning for each kind of withholding is set out in why some values are missing. What is not held at all, and what it would take to hold it, is in the coverage and gaps report.
This is not advice
Hydrionis presents scientific and regulatory information for general reference. It is not medical, legal or engineering advice. Drinking water standards are jurisdictional: a limit applies only where it was made. For a concern about the water at your own property, contact your supplier or the relevant regulator. Nothing on this page limits or replaces the terms.