Project Source Whole Home 2.5" Diameter Standard Single-stage 4-GPM Mechanical Filtration Whole House Water Filtration System. Built in valve-in-head feature makes filter changes even easier.Third party certified for materials safety, reduces sand, sediment and rust from your main water supply. Fits most homes, 3/4" pipe is most commonly used. Designed for homes with 3 or fewer bathrooms. Use with a variety of Project Source filter elements including PS-WHS--MB2, PS-WHS-SW2, PS-WHS-PL2, PS-WHS-CW2, PS-WHS-CB2 and PS-UC-GAC.