Chemical

There are a number of chemical oxidizers that are used to destroy microorganisms in purified water. The most common ones are the following:

• Fluoride
• Hydrogen Peroxide
• Permanganate
• Chlorine
• Bromine
• Iodine

All of these chemicals are more or less readily available in developed countries and they require relatively inexpensive means, i.e. low capital cost to deliver them to the water to be treated.

However, correct and reliable dosing becomes a significant challenge for smaller purification units, as these chemicals are highly aggressive in different ways and deleterious to the water consumer's health even at relatively low concentrations.

Nevertheless, some of them are being used in most of the larger communal systems under strict controls, for example chlorine due to its residual activity that prevents reinfection during long residence times in non-sterile large distribution systems or for addressing specific public health issues such as prevention of dental caries (fluoride) and thyroid diseases (iodine).

In small and remotely located water purification systems the risk of incorrect dosing is too high while the long term health advantages are eclipsed by the predominant need for a short and medium term supply of safe drinking water.