Water has the highest specific heat capacity (4.18 J/g/°C) under normal conditions and is also readily available. As it is so easily accessible, water is the best form of coolant available for many overclockers who prefer liquid cooling. In water-cooling systems, distilled water is mostly used as a coolant. Some people also use raw reverse osmosis (RO) water. You might be surprised to know that you can temporarily bypass the filtration process of a home RO water filter and collect raw RO water (without the minerals) for your coolant requirements.