The concept of multi-rectangular diagrams (MRD) is introduced to replace many classical and triangular coordinates.(Piper diagrams) to examine the multi-variate association of chemical constituents present in groundwater MRD eliminates the drawbacks of classical trilinear diagrams effectively. Comparison between MRD and the classical trilinear diagram is presented MRD is used for the assessment of groundwater quality in Chaj Doab area of Pakistan. The differentiated dominant groundwater types in the study area are sodium bicarbonate, calcium bicarbonate and sodium sulfate. Sodium bicarbonate is the most abundant type of groundwater in the central part of the study area.