Like anything one purchases, the higher the function of the water filter
, the higher its cost. It is better to replace your water filters with at least an equivalent filter or more as you can afford. You might not have a clue on what an equivalent filter is if the existing failed filter shows no indication of any manufacturer or markings. In that case, you would take the failed filter to a store and get assistance to match it to a current equivalent. Also, for older plumbing fixtures, there can be tolerance issues with the replacement filter, since the original part is long gone from manufacturing. In such cases, you might need additional water seal o rings or even a plumber to contain any leakage that was not present before.