Industrial, agricultural and water supply industries rely on the precise monitoring of the water quality so as to efficiently handle polluting effluents before they enter the environment and lead to awful consequences. It is also important to note that very strict European Community and government legislation imposes the implementation of increasingly frequent and wider ranging water quality analyses on wastewater that is discharged into the environment. As a result, the quality demands these industries and end-users make on such monitoring systems are very high, and include efficiency, cost-effectiveness, and precision. Conventional water quality monitoring systems utilise sensors that are not durable or reliable enough for effective long-term field use. In addition, water quality data are traditionally manually recorded while being submitted to extensive data processing. This method is very costly and not always accurate. In order to solve all these problems and meet the demands of water quality monitoring end users, a group of researchers from the Netherlands, UK, Spain and Germany developed and validated a nitrate sensor and pH sensor within one modular instrument that is more flexible, cost-effective, robust and reliable than current technologies. The incorporation of the nitrate and pH sensor into one modular instrument not only advances the state-of-the-art, but also exhibits reduced size compared to existing sensors. Enhanced robustness and reliable effectively meet the needs of the industry, while on-line monitoring increases precision. The market applications for this technology are vast, and include agricultural effluents, water and wastewater industries, groundwater monitoring, and many industrial sectors. In essence, this innovative technology enhances the standards of water quality monitoring systems while being cost-effective.