The Mineral Plus cartridge adds a blend of beneficial minerals for our health, such as calcium, magnesium & phosphates to your drinking water which gives the water its 'body' as well as 'roundness' of taste. Raises the PH Level of reverse osmosis purified water to a balanced 7-7.5Ph. This cartridge should be replaced every 1850 litres, or approx every 12months depending per household, whichever comes first. Part No. 13041.