How much of a Texas water loss figure is actually measured?

The short answer

A water loss audit reports apparent loss — water that reached a customer and was never billed — as three components: customer meter inaccuracy, unauthorized consumption, and data handling error. TWDB supplies a default value for the last two when a utility does not measure them, and records which in its own export.

So a reported apparent loss figure is part measurement and part assumption, and the export says which. Across the published record, unauthorized consumption is a default on 95% of filings and data handling error on 30%.

The regulator's own quality score does not separate them

TWDB scores each audit for data validity on a 0–100 scale, the AWWA M36 instrument. Filings that use at least one default average 68.4 across 9,315 filings; filings that use none average 70.0 across 429 — 1.6 points higher.

That is the finding. A reader sorting by the validity score is not sorting by how much of the figure was measured, because the score barely moves between the two populations. The defaulted share is a separate fact, published in the same export, and it is the one that answers the question.

Both means are over filings carrying a score. The two populations are very different sizes, which is itself worth knowing: filing without any default is the unusual case.

What this does not say

A default is not an error, and it is not a finding about the utility. TWDB publishes these values precisely so an audit can be completed without them being measured, and using one is the documented, intended path. Nothing here says a utility failed to measure something it was required to measure, and nothing here is a pass or a failure of a water balance check — no filing in this corpus is closed or failed. What the defaulted share tells you is how much of a published number is known. That is a different question from how much water is lost, and it is the one to settle before acting on the figure.

The filings leaning hardest on a default

Most recent filed year, where more than half of reported apparent loss is a default rather than a measurement. 459 systems qualify; the 50 highest are shown, each linking to its own page and the cell every figure was read from.

An excerpt, ranked. The other 409 are reachable from the Texas index and each has its own page.

Where the numbers come from

Every figure above is computed from Texas Water Development Board's published water loss audit export at build time, not transcribed. The per-population distributions are published as a file at the distributions dataset. Each system's own page names the archived workbook, its SHA-256, the retrieval date and the cell each value was read from.