Regardless of what water you are using it is very important to protect each house from all the problems municipal and all other waters have with chemicals etc… All are absorbed by your skin when you take showers and baths and when you drink the water. That weakens your immune system. The three stage filters are designed to allow any type of cartridge that is necessary depending on your waters problems. The first stage – Big Blue -1 Micron Particle Filter will prevent sediment, algae, protozoa or large bacteria from passing through. All replacement parts are at a reasonable price. NSF CSA UL CE certified. The item “Whole House Water Filters, 25GPM, 4.5×10, 1 3 + cartridges, CTO, 1 Micron” is in sale since Saturday, March 3, 2018. This item is in the category “Home & Garden\Home Improvement\Plumbing & Fixtures\Water Filters”. The seller is “omnyx66″ and is located in Newport, Vermont. This item can be shipped to United States.