| In this article, I am going to discuss the five most | | | | tastes and odors associated with chlorine residuals, |
| popular treatment methods for domestic drinking | | | | certain organic chemicals and chemical compounds |
| water and their relative merits. | | | | produced by various microorganisms including |
| 'Safe water' does not contain harmful chemicals or | | | | actinomycetes, iron and sulfur bacteria, fungi and |
| drinking water microorganisms in concentrations that | | | | algae. |
| cause illness. 'Adequate water supply' provides safe | | | | 3) Ion exchange resins are used to exchange their |
| water in quantities sufficient for drinking, culinary, | | | | 'soft' sodium ions for the calcium, magnesium and iron |
| domestic and other household needs, in order to | | | | ions in 'hard' waters. These systems may also |
| maintain personal hygiene of the household members. | | | | remove nitrates and sulfates by freeing the water of |
| WHO 1987, Technology for water supply and | | | | mineral cations and anions. |
| sanitation in developing countries, WHO, Geneva, | | | | 4) Distillation units heat the water to a vapor, vents |
| technical report series no.742. | | | | volatile impurities and separate dissolved solids in |
| Commercial devices: | | | | drinking water. Cooling condenses the purified water |
| The point-of-use commercial devices as treatment | | | | vapor back to liquid. Heating the water to boiling and |
| for removal of drinking water microorganisms are | | | | inclusion of an air gap between the raw supply and |
| increasingly becoming popular in many developing | | | | the product water provides an effective barrier to |
| countries. | | | | microbial migration from contaminated source into the |
| There are a number of devices that have been | | | | processed water. Generally, seawater was used in |
| developed as home treatment methods for removal | | | | distillation process to obtain fresh water to use. |
| of drinking water microorganisms from public water | | | | 5) Reverse osmosis (RO) is another popular |
| supplies. Such devices use a variety of basic process | | | | treatment principle in which the dissolved solids in |
| concepts such as filtration for drinking water, | | | | drinking water are separated from the water supply |
| adsorption, ion exchange, reverse osmosis and | | | | by applying a pressure difference across a |
| distillation to achieve a revised contaminant reduction. | | | | semi-permeable membrane. The semi-permeable |
| 1) Filtration devices have been designed to remove | | | | membrane allows the water to flow through but |
| turbidity, particulate materials (such as asbestos) and | | | | prevents dissolved ions, molecules, solids and also |
| certain type of colloidal color in water. | | | | many organisms and imparts a higher quality to the |
| 2) Adsorption by granular activated carbon is a | | | | product water. |
| chemical water treatment system used to remove | | | | |