Groundwater pollution is one of the major threats to sustainability. Policy makers in West Bengal are trying to work out reasonable solution to the growing menace of arsenic contamination of drinking water. The consumption of arsenic contaminated water results in serious damage to people’s health and its effects sometimes prove fatal.

Tubewells and Wells are the main source of clean drinking water in rural West Bengal. In many parts of West Bengal, water from those wells is contaminated by naturally occurring arsenic, above safe limits. It is estimated that in the order of 85 million people in West Bengal are at risk. There have been thousands of reported cases of poisoning and it is generally felt that cases continue to be under-reported. The arsenic contamination problem is also serious in neighbouring Bangladesh, as well as elsewhere in the region.

The SHIS Arsenic Mitigation Program operates under a Bilateral Agreement between the Government, SHIS and UNICEF.
The main purpose of the program is to test and verify the water including monitor the performance of domestic Arsenic removal filter, designed to remove arsenic from water. Furthermore, those tubewells which are passed as safe from the verification process are painted, that allows them to be used safely.
The range of arsenic content varies from 0.055 to 3.20 milligram/litre (mg/l).

Some of the options which are proposed in the awareness camps for providing arsenic-free water to the affected rural population are:

Tapping a deeper third layer beyond 100-150 metres below ground level, which is found to be arsenic-free.
Adopting arsenic removal technique through domestic filters, which even SHIS, is providing at cheaper rate through arsenic removal plants.

SHIS has taken two approaches for its arsenic mitigation programme

• Provide an arsenic-free water supply, that is, an alternative to contaminated tubewells.
• Provide an arsenic testing technology, that is, to check water from contaminated tubewells.

In many rural areas, there are few alternatives to the contaminated tubewells. As a result, household water treatments (Domestic Filter) are familiar concepts in many parts of West Bengal.

SHIS has introduced Arsenic Removal Domestic Filter which follows the concept of the Amal unit, comprises a conventional two-chamber domestic candle filter body, with a layer of activated alumina granules in the top chamber (in place of a ceramic candle filter). The activated alumina media is a granulated form of aluminum oxide that has a strong affinity for dissolved arsenic, and remove it from solution by adsorbing arsenic molecules into its surface. The media has a finite adsorption capacity, but can be regenerated by flushing with sodium hydroxide and acid.

The unit is available in all range of sizes and materials, costing from Rs 1,650 to 2,400 (US$ 38 to 56). The activated alumina costs only Rs 100 per kg (US$ 2.30) and makes up less than 20 per cent of the total cost. The claimed design life of the activated alumina is two years, but several customers have already paid Rs 150 (US$ 3.45) to have their media replaced, and it appears that, in some areas, saturation is reached in less than six months. High iron loads quickly clog the purifier, and require regular removal of the media for cleaning.

Initially, the activated alumina granules were loose and this process was difficult, but now the media is supplied in a porous cloth bag that makes cleaning and replacement easy.

	SHIS believes that there is considerable scope to make the unit more affordable. The SHIS Arsenic Removal Domestic Water Filter is cheap in comparison to other household arsenic removal units, but it is simple to operate and appears to provide good arsenic removal.
SHIS’s main challenge now is to make the Aresnic Removable Filter affordable, so that we can give some hope of better health for the poor underprivileged.

It is clear that arsenic mitigation in the region is an enormous task, and that there is no single solution. A range of approaches and technologies are needed to suit the different locations, cultures, and groups of people, involved.