Is it necessary to change the pre-filters on my system every 4 months?

Yes and this will be scheduled and carried out by our technicians as part of our annual maintenance. Our systems have been designed to operate best to give high quality purified water with normal routine maintenance. By changing the pre-filters on a regular basis, you will eliminate dirt and chemicals in the water that will plug the membrane. After six months of use, the carbon filters can have bacteria growing within the filter media. Your local water conditions may necessitate more frequent filter changes.