Legionella Risk — Monitoring of Shared Domestic Hot Water Systems (Odoo 19 Community)

Legionella Risk — DYONYSOS

Health and safety logbook for shared domestic hot water systems (Legionella control), on Odoo 19 Community. Builds on the free base Mandatory Periodic Inspections.

Also searched as: Legionella health logbook, Legionella pneumophila analysis, 1000 CFU/L threshold, domestic hot water temperature log, Legionella monitoring for hotels, campsites and nursing homes (EHPAD).

The legal basis, cited in full. French Order (arrêté) of 1 February 2010 on the monitoring of Legionella in domestic hot water production, storage and distribution installations: analysis for Legionella pneumophila at least once a year, threshold of 1,000 CFU/L. Order of 30 November 2005 on maintaining network temperature.

Who it is for. Hotels and holiday residences, campsites, nursing homes and social care facilities, healthcare facilities, gyms and shared locker rooms, boarding schools, multi-unit housing. Anywhere people shower: Legionnaires' disease is not contracted by drinking, but by breathing in an aerosol.

An exceedance cannot be closed without a follow-up test. This is the blocking rule, and it is the one that matters. A spreadsheet records the exceedance, records the works, and stops there: no one comes back to check. It is not the exceedance that kills, it is the exceedance believed to be resolved. The module refuses to close it until a subsequent follow-up test on the same system has come back below 1,000 CFU/L.

The required action is calculated, never chosen. Below 250 CFU/L, routine monitoring; from 250, heightened vigilance; from 1,000, immediate corrective measures and a follow-up analysis; from 10,000, a heightened internal DYONYSOS alert.

The order of February 1, 2010 sets only 1,000 CFU/L (art. 4) as the regulatory threshold here. The 10,000 CFU/L level is a precautionary value chosen by DYONYSOS (SEUIL_ARRET = SEUIL_UFC * 10, internal setting), triggering a heightened alert; it is not a threshold set by the order. Restricting or shutting down points of use and notifying the ARS (regional health agency) are the responsibility of the operator and subject to the ARS's requirements.

Source: https://www.legifrance.gouv.fr/jorf/id/JORFTEXT000021795143 — accessed on September 27, 2026 (reference taken from VERIFICATION_REGLEMENTAIRE.md, section IV).

The temperature reading is the cause; the analysis is only the finding. The module assesses each reading according to the point where it is taken: at least 50 °C at the point of distribution and at the loop return, at most 50 °C at the point of use in a room intended for washing, where the risk becomes scalding. The same network must be hot everywhere except at the tap — that is the challenge of the trade, and a single threshold misses it.

The due date comes back on its own. Recording the result of an analysis logs the inspection in the register: the annual analysis comes back automatically, with its alert.