Well water in the northern parts in Sri Lanka is encountering with the problem of water hardness. Hardness definition: A. Hardness is the term often used to characterize a water that : ü Dose form a foam or lather well and cause soap scum Ca2+ + (Soap)-↔ Ca(Soap) 2 (s) This … 2 Water Softening 1. Water of required quality for its intended 59 use should be produced by appropriate methods. According to the Sri Lanka Standards for potable water – SLS 614, the highest desirable level of total … 64 The principles may be applied to other qualities of water … Types of Water Softening Methods Ion Exchange. Generally, it entails exchanging the magnesium and calcium ion contained in hard water … 60 61 2. Ion exchange is the oldest and most common method of water softening. SCOPE 62 2.1.63 This document provides guidance for the production of Water for Injection (WFI) by means other than distillation. Water softening In water softening a cation resin in the sodium form is used to remove hard metal ions (calcium and magnesium) from the water along with troublesome traces of iron and