Multiparameter Optical Probes and IoT Networks for Real-Time Water Quality Monitoring

Access to safe water is increasingly challenged by agricultural runoff, wastewater discharges, and diffuse pollution. Current country-wide monitoring relies heavily on manual sampling and accredited laboratory methods, which are costly, logistically demanding, and limited to a few measurements per year. These constraints leave regulators and water managers without sufficient temporal resolution to identify pollution trends or respond rapidly to emerging threats.

We present a work in progress of a novel multiparametric optical probe capable of simultaneously measuring key water quality parameters, including nitrates, turbidity, Abs@254, water quality index, and temperature. The device requires minimal maintenance, is cost-effective, and has been validated against accredited laboratory methods to a practical extent. While inherent differences exist between in-situ optical sensing and gold-standard analytical techniques, the advantage lies in frequency and affordability: our system can record measurements every 15 minutes, powered by batteries or solar panels, and is suitable for long-term field deployment.

When constant trends are observed, laboratory validation may be unnecessary, but deviations trigger an early warning and targeted manual sampling. Over time, such probes complement rather than replace accredited methods, significantly increasing data availability while reducing the cost per measurement to cents. This high-frequency data stream enables tracking both stable and shifting water quality trends, supported by first-principle modeling or AI-based applications for aquatic environments.

The concept is already being tested in partnership with the National Water Testing Laboratory at the Water Research Institute Slovakia, within the framework of the EU Nitrates Directive. Their national network of approximately 1,200 groundwater wells, of which around 200 exceed the nitrate health standard, provides an ideal platform to evaluate the system. By combining in-situ sensing with IoT connectivity, this approach enables scalable, data-driven environmental protection and supports compliance with European water quality policies.

Project sponsored by the Agency for Research and Innovation Slovakia, APVV-23-28205.