The collective sewage system network of a municipality is not mapped in a single document accessible everywhere in the same way. Depending on the size of the community and its level of digitization, the pipe plan may be found at the town hall, on an intercommunal portal, or via a national tele-service. Locating the sewer network map requires knowing which contact person holds the information and in what form it is available.
INERIS Tele-service and DT-DICT Declaration: the regulatory framework to know
Before searching for a plan, it is essential to understand the system that structures access to data on buried networks in France. The tele-service “Building without Destroying,” managed by INERIS on behalf of the Ministry of Ecological Transition, centralizes information related to network operators in a given area.
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This portal does not directly provide a detailed plan of the sewage pipes. It identifies the operators concerned by a parcel and allows the initiation of the DT-DICT declaration (Project Work Declaration, Intention to Commence Work Declaration). This consultation has been legally framed since the decree of October 5, 2011, for any work project near buried networks.
In practice, the tele-service is mainly used by construction professionals and project owners. An individual preparing a connection or extension can use it to identify the manager of the sewage network in their municipality and then contact them to obtain the sewer network map corresponding to their needs.
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Intercommunal Mapping Portals: Free Access to Sewage Plans
The most direct source for consulting a sewage plan remains the GIS (Geographic Information System) portal of your intercommunal community or sewage syndicate. In recent years, many intercommunal structures have transitioned their data to online maps accessible without account creation.
These portals generally display several overlapping layers of information:
- The collective sewage zoning, which delineates the areas connected to the sewer system and those subject to non-collective sanitation
- The layout of the main collectors and secondary branches, sometimes including the diameter and material of the pipes
- The existing connection points, lift stations, and treatment plants
- The cadastral background, which allows users to locate their parcel and verify the proximity of the network
The Geographic GIS (SiiG), for example, offers this type of public access and serves as a model for other syndicates and EPCI. However, the quality of the data varies from one community to another: some display only zoning, while others publish the complete layout of the pipes.
Finding Your Intercommunal Portal
The name of the portal is not standardized. Searching for the name of your community or metropolis followed by “sewage mapping” or “online GIS” usually yields usable results. The websites of water and sewage syndicates often have a dedicated tab.
Not all municipalities have an online mapping portal. Small rural communities sometimes keep their plans only in paper format or in unpublished internal files.
Request at the Town Hall and Urban Planning Service: the Classic Approach
When no digital portal exists, the town hall remains the entry point. The urban planning or technical service holds the plans for the municipal sewage network. Depending on the municipality, consultation may take place on-site, by appointment, or after a written request.
Two elements deserve to be distinguished:
- The public network plan, which shows the layout of the pipes in the roadway and public areas. This document is in the public domain, and its consultation cannot be refused
- The individual connection plan, which documents the connection between a private property and the collective network. This document is provided to the owner during the initial connection and may be required during a real estate sale
If you are preparing a real estate transaction, the sanitation diagnosis (mandatory in the relevant municipalities) includes a verification of the connection. The compliance check and the connection plan are two distinct documents: the first assesses the condition of the installation, while the second describes its physical layout.
Collective Sanitation Zoning: Check Before Searching for a Plan
Before any search for a plan, it is essential to ensure that the parcel is indeed located in a collective sanitation zone. The sanitation zoning is a document annexed to the Local Urban Planning Plan (PLU) of the municipality. It distinguishes areas served by the public network from those where individual sanitation (septic tank) applies.
Consulting this zoning avoids unnecessary searches. A parcel classified as non-collective sanitation is not intended to appear on a sewer network plan, as no public pipeline serves it. The zoning can be consulted at the town hall, on the national collective sanitation portal of the ministry, or directly on the urban planning geoportal.
National Data on Collective Sanitation
The national collective sanitation portal publishes data by municipality (connection rate, name of the manager, contact details of the service). This information allows for quick identification of the right contact person without going through the town hall. The updating of this data is regular, making it a reliable starting point.
For a connection or work project near the network, starting with zoning and then identifying the operator via the INERIS tele-service remains the most effective sequence. Consulting the detailed plan comes next, either from the identified manager or on the intercommunal GIS portal when it exists. The paper plan at the town hall remains the last resort, but it works in the vast majority of cases.