This technical paper was abstracted from the main presentation held on World Water Day 2012 organized by Royal Society of Chemistry and The Environ Monitor. The paper reviews the water quality problems of Pakistan, and the decline in the available water quantity. The four major water quality problems of Pakistan are discussed. Owing to the theme of the seminar, i.e. "Chemical Treatment of Water for Pakistani Communities", this particular manuscript explains the principle and chemistry of the three main chemical water treatment processes, namely, the coagulation, flocculation and lime-soda water softening process. The aim of the manuscript is to explain the concept of designing these water treatment units.