The Pentair OMNIFilter Whole Home 10-Inch Heavy Duty Big Blue system filters at the point where water enters the house, so every tap, shower and appliance draws from the same treated supply. Catching sand, silt and rust on the main line also helps protect water heaters, dishwashers and the plumbing behind the walls. It connects to a 1-inch NPT line and takes a large-diameter Big Blue cartridge for strong flow and long life between changes. The valve-in-head design is what makes maintenance painless. The head stays plumbed into the line while the sump unscrews, and a built-in bypass lets you divert water around the housing with a half turn of the handle, so the household is not left without water while you swap a cartridge. Water is unfiltered during bypass, so keep the changeover short. A red pressure relief button vents trapped air before the sump comes off. The box holds the housing with its valve-in-head cap, a housing wrench and a mounting bracket with hardware. The cartridge is sold separately so you can target your own water: pleated, string wound or polyspun cartridges for sediment, or carbon block and radial flow carbon for chlorine taste and odor. Seat the O-ring level at every change and hand-tighten until snug. For cold water use only.