UV-visible spectrophotometry in mainly used for the measurement of specific substances and aggregate parameters in water and wastewater. However, other applications for physical parameters like measurement or characterisation of colour or total suspended solids can be proposed. After a brief presentation of colour measurement of water, the physical diffuse absorption related to the interaction between nondissolved matter and UV-visible absorbance is studied. UV-responses of mineral suspensions and wastewater are presented and optical properties of microorganisms in water are also considered regarding recent works on the topic. Finally, the TSS estimation by UV-visible spectrophotometry is studied after a discussion concerning the relevance of turbidity for water quality monitoring.