In India, (especially in rural area), more than 50% of the population consumes unsafe, contaminated and polluted drinking water. Due to poor water quality, the occurrences of intestinal diseases are wide spread and rural community spend substantial portions of their income every year to cope with the water borne diseases. In recent years, the market for various commercially manufactured filters has grown in India. These filters are far too expensive for most of the Indian population.

Keeping in mind the personal health of common rural people, SATHI with technical support of SAPWII (South Asia Pure Water Initiative, Inc.), has developed very simple & affordable water filter. This water purification filter is a type of slow sand water filter specifically designed for removing disease causing organisms with intermittent operation. The filter is composed of a cast concrete container with layers of sand and gravel and a naturally occurring biological layer in the top few centimetres of the sand layer. The filter is very effective in removing 98% of bacteria, 100% of viruses, 99% of protozoa, amoebas, metals, and worms, 95% of iron, and with a slight modification, 93% of arsenic.

Besides, maintenance cost of filter is negligible. Once installed, the filter will last 25-30 years, producing 80 litres per day of pure and safe drinking water. It is helpful in reducing water borne disease such as typhoid, cholera, hepatitis, e-coli, dysentery, among many other viruses and infections. Till date, SATHI has constructed & installed more than 5000 such filters in 185 remote villages of Pachhad, Nahan & Paonta-Sahib block of Sirmour district of Himachal Pradesh, and 180 filters in 15 villages of adjoining Morni Hills area of Haryana . Besides, through practical training & demonstration, SATHI is also spreading this affordable & innovative technology of water purification in other remote & backwards rural regions of state.

In addition of concrete variant of filter, SATHI also developed an improved version of filter Stainless Steel variant. The newly developed lightweight (4.5 Kg) stainless steel bio-sand filter has an edge over concrete filters, overcoming many shortcomings (especially related to heavy weight of concrete filters & difficulty in transportation in hilly area) and providing better quality control. Besides improving its appearance, stainless steel adds to the strength, reliability, durability, and portability of the filter. Besides, likewise concrete filter, stainless steel variant also does not require any replacements parts / maintenance. With support of UC Berkeley ( Project RISHI), SATHI has successfully installed 132 stainless steel bio-sand filters in Bahrog Baneri village of Ponta Sahib Block, Distt . Sirmour (HP) and made 05 wards 100 % purified.