Among these, ion selective electrode methods are most widely used. However, there are several disadvantages associated with this method such as the requirement for complex instruments, well-equipped laboratories and trained personnel. There are also other issues associated with these methods such as low specificity and inefficient performances at higher concentrations. Hence, neither the ion selective electrode nor the NMR approach can be used in minimally resourced communities. As a result, colorimetric and fluorescence sensing systems are emerging as an alternative to such complex systems due to their easy field deployment advantages along with high sensitivities and extremely low detection limits. These become more attractive for limited resource communities that cannot afford the establishment of well-equipped laboratories.