I moved to a new house and found a 10" big blue water filter installed under the kitchen sink, of the type that would normally be whole-house. The water tastes off and I am assuming that the cartridge needs replacing, since it looks pretty filthy and I am fairly sure it has not been changed in several years.

I found these instructions for changing the cartridge. However, there seem to be a hundred types of replacement cartridges. I tried to look at various DIY and plumbing sites, but I still have no idea what type of cartridge is appropriate for filtering New York City tap water, or even whether this is a bad idea and I should replace the whole thing with a standard under-sink filter. Pleated? String? How many microns? Etc. It's all Greek to me, so any advice is greatly appreciated.

1 Answer 1


...you have some of the best tap water in the country. Either remove it completely, or possibly use a carbon filter cartridge if there's enough chlorine to bother you. If the filter looks off, the filter housing probably needs a good cleaning/sanitizing.

Which one (or how many) of the bottled water companies is just bottled NYC tap water?

  • 2
    +1000. NYC tap water consistently wins blind taste-tests and health tests over fancy bottled waters. It's brought in via major aquaducts from reservoirs many miles upstate carved through solid rock, then distributed through a relatively modern system. Any contamination is going to be transient and harmless, rust knocked free when pipes were being worked on. I would guess the prior occupant was unreasonably paranoid about chlorination and fluoridation, and that the filter unit shouldn't be there in the first place, unless the building is KNOWN to have special problems of its own.
    – keshlam
    Commented Nov 10, 2014 at 4:19
  • I think the concern was old piping. I'm frankly not sure how to even figure out if that's a problem.
    – Corey G
    Commented Nov 10, 2014 at 4:29
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    If you're concerned, sending a sample of the water to a testing lab will set you back about $20, and they'll give you a full rundown. (Filter salesmen may offer free tests, but that isn't exactly an unbiased opinion.) BTW. websearching "new york city water" will find the city's statement, history of the system, and plenty of discussion about how good the water quality is.
    – keshlam
    Commented Nov 10, 2014 at 5:03
  • Does the fact that the existing cartridge is covered in brown sludge not imply that it was necessary?
    – Corey G
    Commented Nov 10, 2014 at 15:10
  • 1
    Not really. Filter media (particularly when not changed for a looooong time) provides an ideal environment for some stuff that otherwise would never be an issue. In particular, a housing that transmits any light increases the odds of growing algae immensely over a nice dark pipe. Poor sanitation when changing filters can add other things you'd avoid by not having the filter.
    – Ecnerwal
    Commented Nov 10, 2014 at 22:08

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