Water is a transparent and nearly colorless chemical substance that is the main constituent of Earth's streams, lakes, and oceans, and the fluids of most living organisms. Water contains minerals of which some are important and some are harmful for human body. We, here, have described process to purify water. Now a days the problem of Arsenic and Lead in drinking water is creating hazard for the people of Pakistan. This paper includes process for the removal of lead and arsenic from water. Two types of techniques were employed for water purification i.e Ion Exchange Method and Reverse Osmosis Process. Reverse Osmosis method is a modern technique and relatively much easier than Ion Exchange method. Some tests like PPM of TDS, PPM of chlorides, PPM of total hardness, PPM of temporary and permanent hardness, PPM of total alkalinity in water were performed to check the quality of water purified. The conclusion from the Experimentation on samples obtained from the above mentioned techniques showed that RO is better technique than Ion exchange method. Ion exchange method is old and more time consuming simultaneously more energy consuming than an RO technique. Many of the modern plants in Pakistan are incorporating RO technique for water purification as it is simple and no need to deal with chemicals. ENGRO has upgraded its plant to RO. Further many small scale plants are shifting towards this technique. The facts mentioned have been verified from physical operating plants in Lahore and Gujranwala.