C-DRONE GUIDE · 31 JULY 2026
Cooling-tower drone inspection: structure, corrosion, Legionella context, price
A cooling tower rejects heat from a process or air-conditioning system by trickling water through an air stream: efficient, but also a structure permanently exposed to moisture, deposits and corrosion, and a sanitary hotspot known for Legionella risk. In France these installations fall under ICPE heading 2921 and strict monitoring. Visual inspection of the structure — basin, fill, drift eliminators, framework, fan — usually demands work at height, in a humid atmosphere, sometimes in confined space. The drone does part of it from outside and from above, without scaffolding or a long shutdown. Here is what it usefully inspects, what it does not replace, and prices observed in 2026.
Published on 31 July 2026, reviewed on 31 July 2026 — regulations in force as of July 2026.
What deteriorates on a cooling tower
Whether concrete, galvanised steel, GRP or timber, a tower lives in an aggressive environment: water, oxygen, heat, chemical treatment. The classic defects: corrosion of steelwork and anchors, cracking and spalling of concrete exposing reinforcement, fouling and deformation of the fill, degradation of the drift eliminators (which, when failing, increase aerosol carry-over and hence sanitary risk), and fatigue of the fans and their mounts. These pathologies are long documented: a review by Bamu and Zingoni published in 2005 in Engineering Structures surveys half a century of defects observed on cooling-tower shells — cracking, rebar corrosion, concrete spalling, geometric imperfections (see the study on Google Scholar).
The common thread: most of these defects first appear at the surface and up high, where a ground inspection sees nothing. That is precisely the drone's ground.
What the drone inspects — and the link with sanitary risk
The drone documents the structure from above and up close: state of the crown and fans, corrosion of panels and framework, condition of accessible drift eliminators, visible fouling of the fill, fixings and anchors. A thermal flight sometimes complements the visible one to spot hot points on fan motors. The benefit is twofold: safety (no technician exposed at height in a humid atmosphere) and a repeatable overview from one visit to the next.
This structural check indirectly touches sanitary risk. A study by Campaña, Del Hoyo, Monleón-Getino and Checa published in 2023 in the International Journal of Hygiene and Environmental Health, covering 127 towers and evaporative condensers, links Legionella colonisation to physicochemical parameters, notably scale, sludge and corroded material (see the study on Google Scholar). In other words, the corrosion and fouling the drone spots are not only a mechanical issue: they feed the biological ground that ICPE heading 2921 requires operators to control. The drone documents; it does not replace water analyses or the regulatory monitoring log.
Flying on an industrial site and complementary inspection
A cooling tower is rarely in open country: roofs of office buildings, industrial sites, hospitals. The flight is prepared like any constrained-environment job — airspace check on Géoportail, coordination with the operator, and the warm humid plume leaving the tower factored into the trajectory. In built-up areas, the framework is the one recalled in our flying in cities guide.
Detected defects are increasingly read from 3D surveys: a study by Makuch and Gawronek published in 2020 in Remote Sensing shows that point-cloud analysis automatically detects and measures the defects of a tower shell (cavities, scaling) without human intervention on the structure (see the study on Google Scholar) — a cloud drone photogrammetry can also produce. The drone nonetheless remains a triage and monitoring tool: statutory inspection, structural assessment and internal-fill checks require physical access and a specialist office. For internal components out of reach, see our confined-space drone inspection guide.
Prices observed in 2026
Ranges observed in 2026 (excl. VAT):
- Visual inspection of a tower or cooler (external flight, structure and crown, geolocated photo report): €500 to €1,000.
- Bank of several towers on one site (industrial, hospital): €900 to €2,000.
- Thermography option (fan-motor hot spots): €300 to €700.
- 3D survey for shell-defect monitoring (point cloud, visit-to-visit comparison): €800 to €2,500 depending on height.
The visit is scheduled for a shutdown or reduced-operation slot agreed with the operator. Request a quote stating the tower type, material, number of structures and setting (roof, ICPE site).