Alkaline water is water with a higher-level pH, typically 8 or 9, than regular drinking water which is generally a neutral pH of 7.
A reverse osmosis system is one of the popular methods used to create alkaline water. The reverse osmosis process will remove all contaminants and minerals and a remineraliser cartridge will add minerals back to the water which will raise the pH level of the water to be alkaline.
A small number of studies suggest drinking alkaline water may offer additional health benefits including relief from acid reflux, lowering of fatigue levels post intense exercise, relief from high blood pressure, diabetes and high cholesterol and limiting of contaminant exposure.
You can learn more about the health benefits of drinking alkaline water here.