Real-time culvert monitoring for UK councils. Continuous water-level sensors give operations teams early warning before overtopping — not a phone call after the road closes.
Storm Babet in October 2023 caused catastrophic flooding across England, particularly in Yorkshire, Lincolnshire and the East Midlands. In many cases, culverts blocked by debris backed up silently until roads were overwhelmed. Lead Local Flood Authorities are obligated under Section 19 of the Flood and Water Management Act 2010 to investigate significant flood events, yet most culverts are only inspected on a two-yearly reactive cycle, if at all.
Section 19 investigations required after significant flood events: continuous data supports your statutory duty
Typical reactive inspection cycle for culverts. Blocked inlets can fill silently between visits
Average cost of a gully clean and road closure following a culvert-related blockage incident
LLFAs — Lead Local Flood Authorities in England, each with a statutory duty to manage flood risk from ordinary watercourses and culverts
The system runs on standard off-the-shelf hardware: no proprietary lock-in, no cellular dependency, no mains power required.
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A waterproof ultrasonic sensor (JSN-SR04T) is mounted at or near the culvert inlet, pointing downward toward the water surface. It fires a 40kHz pulse, measures the echo return time, and calculates the distance to the water surface. The device wakes every few minutes, takes a reading, and transmits over LoRa radio, then goes back to sleep to preserve battery. No mains power. No cellular SIM.
A single gateway, a small weatherproof box mounted on a rooftop or utility pole, receives transmissions from sensor nodes up to 2km away in urban areas and further in open terrain. One gateway can serve dozens of sensor nodes across an area. It connects to the internet over ethernet or WiFi and forwards readings to the server. If LoRa coverage is unavailable at a site, a mobile data connection can be used as a fallback.
Once the gateway receives a reading from a sensor node, it passes the data to a server that decides what to do with it. This is where the alert rules live: if the water level crosses a set threshold, an alert fires. The server is privately operated, meaning your council's data stays under your council's control. Over time, readings are correlated against Met Office rainfall data to build a clearer picture of which culverts are most at risk and when.
When a threshold is breached, a webhook fires within seconds, delivering an alert to email, SMS, or an operations dashboard. The early warning gives highways and drainage teams time to inspect, close roads proactively, or deploy temporary measures. All data is logged, providing the continuous sensor record that supports Section 19 flood investigations.
LoRaWAN is the preferred technology, but the sensor hardware works with multiple connectivity options. If LoRa coverage doesn't reach a specific site, we switch the radio module and keep everything else identical.
A single upstream sensor gives you two distinct alert types: flood early warning and blockage detection, from the same hardware.
During intense rainfall, upstream water backs up against the culvert as flow exceeds capacity. The sensor detects the rising surface and fires an alert before overtopping, giving highways and drainage teams time to respond before road damage or property flooding occurs.
When debris blocks the culvert inlet, water backs up faster than rainfall alone would predict. If the sensor is mounted directly above the inlet, floating debris also reflects the ultrasonic pulse back sooner — giving a falsely high reading that triggers an alert. A blockage caught in dry weather is easy to clear. During a storm it becomes a Section 19 investigation.
Adding a second sensor downstream allows direct flow differential measurement. If upstream is rising but downstream is not, the culvert is blocked. This gives maintenance teams a precise, actionable signal even without rainfall context.
A single avoided callout nearly covers two full years of monitoring.
One-time fee. Covers site survey, gateway hardware, mounting, configuration and commissioning. One gateway typically covers a 2–5km radius.
One-time per node. Includes sensor hardware, installation and configuration. Up to 50 nodes per gateway — additional gateways available for larger networks.
Per node per year. Covers platform access, real-time alerts, data storage, remote monitoring and an annual site visit.
We are now accepting applications from Lead Local Flood Authorities in England for the first pilot cohort. The programme is structured in three stages, each evidence-gated before committing to the next. No operational dependency is required at any stage.
We start with a site survey to identify the best candidate culverts in your area. We then install one sensor node at a priority location. Data streams to a shared dashboard with simple threshold alerts. We handle everything — installation, configuration and monitoring. No operational dependency; data is advisory only.
Following a successful pilot, expand monitoring to your priority culvert network. Each additional node deploys in half a day. One gateway typically covers 10–15 culverts within a 2–5km radius. Data from multiple sites feeds a single dashboard, enabling your team to see catchment-level patterns and prioritise maintenance across your monitored network.
As your sensor network matures, we are developing predictive capabilities — correlating water level trends with Met Office rainfall forecasts to alert your team before levels begin to rise, not just when they do. This is on our development roadmap and available to pilot partners as it develops.
Tell us about your council and your priority culverts. We'll confirm if it's a good fit and outline the next steps. No commitment required.
Or email directly: james@culvertsense.com