This kitchen has an extra faucet. It is smaller than the main faucet.

It appears to bypass both the water heater and water softener. It also appears to not have any aeration (no bubbles even when turned up to full stream)

There is a symbol that looks like a water drop crossed out. Also it appears to have a reservoir because after the faucet is in use for a while (e.g. a cooking pot full) the stream gets weaker and weaker, until it sits for a few hours to fill up again

What is it for and does it have a name? Since it seems to not be softened, how do the pipes leading to it not get corroded?

Location: Chicago, IL on a private well


Here's some pictures under the sink. Actually I don't see anything that resembles a reverse osmosis filter (the red thing is a garbage disposal). But the faucet is an exact match to some GE reverse osmosis faucets, so I guess the filter itself is somewhere else. Next to the sink are a dishwasher and cabinets and there is definitely no filter in them either.

garbage disposal pipes

  • Maybe it's hooked up to a well, as opposed to municipal water. Do you have a water pump anywhere?
    – Machavity
    Commented Dec 19, 2018 at 15:43
  • Sounds like some kind of filter can you look under the sink and see if there are any filters? At first I was thinking a small on-demand hot water heater but nothing was said about the water being heated.
    – Ed Beal
    Commented Dec 19, 2018 at 16:42
  • @Machavity the whole house is on a private well
    – ferret
    Commented Dec 19, 2018 at 18:16

2 Answers 2


Based on the fact that it gets weaker after running for a while, I'm going to guess that it's a reverse osmosis water filter.


Thanks to longneck for the tip. It is indeed a GE reverse osmosis filter. Usually the filter itself is installed under the sink but in my case it was in the crawlspace. It has separate piping directly from the well, so it does not go through the water softener first.

The mysterious symbol on the faucet is a filter replacement indicator. It will light up amber when the filter is supposed to be replaced (on a 6 month schedule). Mine has never lit up in 2 and 1/2 years because it's powered by a CR2032 battery that needed to be replaced.

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