Water is the quintessential element of life. In the arid zones like Rajasthan, India, rainfall is scanty and ground water table is too low to satisfy the needs of living beings. One of the water sources is harvesting rain. Though the rainwater does not have its own contaminants but when it touches the surface, it gets contaminated (physically, chemically and biologically). The water thus harvested is used for drinking/ domestic purposes. Drinking water need to be freed from microbial/ disease. Literature indicates the usage of bacteria for self-healing concrete but no study indicates the use of bacteria, Bacillus Licheniformis (BL) or Bacillus Subtilis (BS), for the purification of water. These bacteria can survive high temperatures and can exist in spore form to resist harsh environments or in a vegetative state when conditions are good. In present study two bacteria BL and BS are tested. These bacteria feed on the organic contaminants present in water and produce harmless end products. Cultured bacteria are mixed in concrete to make slabs or sprayed on plain slabs with different combinations. The efficiency is analysed by testing the polluted water samples before and after passing through the slab. Results indicate that water is potable.