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Inspecting sewers by drone: ensuring 100% coverage

Published by Josh Spires on 14 July, 2021, updated on 14 July, 2021.

Inspecting sewers by drone: ensuring 100% coverage

As a part of its everyday work at, Suez RV Osis, a French water and waste management company inspections of its sewer lines must be completed to ensure the network is working correctly and there is no issue that could result in a shutdown. This can be tricky work for humans, so the company has turned to the Flyability Elios 2 to get the job done.

The sewer inspections are crucial for the maintenance of the wastewater systems because they help:

  • Identify clogging in pipes through the accumulation of material or sediment.
  • Assess the current functionality of the network.
  • Identify any potential structural problems that could cause a collapse of masonry and lead to the failure of the sewer network.

French law

Sewer inspections are more important than ever in France right now because of a new national law that requires all major cities in the country to have their wastewater infrastructure inspected and diagnosed by 2026. The law has put tremendous pressure on cities, making them turn to experts in the field like Suez RV Osis for help.

Getting the job done

Traditionally, inspectors at RV Osis have used a variety of methods to collect visual data inside sewers. These include using dollies or carts to roll a camera through a pipe, floating a CCTV camera inside the pipe, or having an inspector go through the pipe in person with a camera. But these approaches are limited and are only useful up to a certain point.

This is especially true for manual data collection, since many of the pipes that Suez personnel inspect present a significant danger for entry due to: 

  • The risk of collapse caused by premature wear of the masonry
  • High water levels caused by heavy rains
  • Slippery areas, which increase the chances of falling
  • The potential presence of harmful gases like Hydrogen sulfide (H2s)

Because of these limitations, only about 80% of the wastewater systems that Suez oversees can be inspected using traditional methods.


To get 80% up to 100% the team turned to Flyability’s Elios 2, which can provide inspectors with remote access to areas that present dangers to inspectors for direct entry.

Using traditional methods, Suez inspectors can inspect about 400-600 meters (1,312-1,968 feet) of wastewater infrastructure a day. But with the Elios 2, it can inspect up to 900 meters (2,952 feet) a day, increasing its inspection speed by anywhere from 50% to more than double what it can achieve using traditional methods.

Using sparse points clouds generated by the software, inspectors can pinpoint the specific place in a pipe that requires maintenance and share that information with other stakeholders in the maintenance process. The precision of the locational data provided by Inspector 3.0 allows RV Osis’ clients to dig right to the place that requires maintenance, without having to waste time digging to the wrong place.

At RV Osis, the term “inspection flight” encompasses a series of steps taken by the inspection team:

  • Step 1: Upstream work & planning. To start out, pilots plan the flight with local inspection teams, including considerations about access, security, and the extent or need of aerial equipment (i.e., drones).
  • Step 2: The flight. When conducting an inspection flight, the drone pilot works closely with the wastewater inspector overseeing the inspection, ensuring that they’re getting all the visual data they need.
  • Step 3: Downstream work & reporting. After all the data has been collected for the inspection, inspectors process the data following a specific series of steps, including the use of photogrammetry to create 3D models where needed. This data is used to draft an official report following the national requirements, which includes the findings from the inspection.

Credit: Flyability

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