Princeton Water Hardness & Quality Report (2026)

Princeton, New Jersey, in Mercer County — a major central New Jersey world-renowned university community (Princeton is one of the most celebrated university towns in the world — home of Princeton University (a member of the Ivy League and consistently ranked among the top 1–2 universities globally; Princeton's campus is one of the most beautiful university campuses in the United States — a magnificent collegiate Gothic and Romanesque Revival campus; Princeton has produced more US presidents, Nobel laureates, and Fields Medal winners per capita than almost any other institution); Princeton is also home of the Institute for Advanced Study (one of the most important centers of pure research in the world — where Albert Einstein spent the final 22 years of his life)), a diverse Mercer County community with a highly international academic, professional, and student population, home of Princeton's Palmer Square (one of the most attractive historic downtown squares in New Jersey), and one of the most intellectually renowned communities in the world — draws its municipal water supply via American Water. Water hardness in Princeton measures 168 mg/L — classified as hard.

Princeton's hard supply reflects the central New Jersey Triassic Piedmont Newark Basin watershed's calcareous-moderate geology. The Princeton Water draws from the Triassic Newark Basin Lockatong and Brunswick Formations (calcareous-moderate). American Water treatment produces the hard 168 mg/L.

At 168 mg/L, Princeton residents face regular hard water challenges. Monthly descaling is recommended. American Water consistently delivers water meeting all New Jersey DEP and EPA Safe Drinking Water Act requirements.