One entry per installation. A pump pulled and reinstalled gets a new entry with the same serial number. The current pump is the one without a removal date.

One entry per installation of a totalizer (water meter). Device facts only: every register value, including the installation and removal readings, is a reading in Production.

How the well is intended to run from a given moment. A change of regime is a new entry; the latest one already in effect is the regime in force. A stopped well is a status change in the history log, not a zero flow.

Append-only ledger of water produced: meter readings and declared volumes. Entries are never edited — a correction is a new entry that retracts the original.