Water Filter Hookup

Hello. I hope I’m posting this in the correct area. I thought I’d share with you the easiest (and correct!!!) way to connect a water filter to any compression fitting, like underneath your sink. It’s not hard, and I thought this might help someone avoid a leak somewhere along the way. I am in no way a plumber, but my buddy is, and I trust his knowledge & advice. For those of you interested after reading, there are a few amazon links at the bottom.

So your water filter is likely going to come with pex tubing. It’s called poly tubing as well. They’re both the same thing, cross-linked polyethylene pipe. As you can see here, mine has a standard hookup for 1/4" pex tubing.

I have a 1/2" pipe servicing my kitchen sink faucet which is connected by a 3/8" compression hose though. This is a common setup for a kitchen sink in the usa, and it should look something like below. This is actually my hot water line, as it’s easier to see.

So if I don’t want to make this harder than it has to be, what do I do? I found a compression shutoff valve with a 1/2" inlet, and 1/4" & 3/8" outlets. It can even turn one, the other, or both off with a simple twist! I was stoked, because now I could connect that 1/4" pex tubing right up to most used drinking water line, without having to resort to a threaded hookup. Which is good, because I don’t have one for drinking water.

The real key to making this work however is the 1/4" brass insert shown below. It allows you to tighten the nut around the ferrule and keep the tube in place without degradation of your poly to brass connection. This will stop leaks from occurring. You could do it without the insert, but it will eventually leak unless you do it right. If you’ve ever had a fridge leak, I’m told this is the most likely culprit.

You don’t need to glue it up, or anything tricky. It’s a compression fitting, so just make sure the nuts are tight, but not too tight Easiest way to do this with the 1/4" line, is by sticking the ferrule ring inside the nut before you put it on the pipe, and lightly tightening it once you match up the holes.

Then hook it all back up, turn your water on, and let her rip. Keep an eye out for any leaks, but it’s pretty simple so there shouldn’t be. Not with that little brass insert in there anyway! Now I have a clean source of ph’d and carbon filtered water for my grows. Pretty easy for someone who’s not a plumber.

Oke doke, I hope this helps someone. I’m trying to get better with the forum before I start my first grow journal soon. Be on the look out for more long winded, unsolicited, yet hopefully informative posts from me in the future! I feel like it’s the least I can do after finding so many good answers here, without even having to ask the question myself. So thanks.

Hydrologic SmallBoy Water Filter

Dual Compression Outlet

Brass Insert

I really didn’t talk too much about my filter. It’s a dechlorinator/sediment filter. When I eventually move out, I can just hook it up to a filter faucet, and it doesn’t look weird that I have a filter with no real hookups. Here’s an extra photo of why you always need to let your new filter flush for a good 10 minutes before you use it. Carbon water lol


got this for 20$ at resale shop everything in the box still. my husband has installed pex before so score! I did not know about the brass insert so thank you!


That’s exactly how mine is installed, only it’s a bathroom sink…like, exactly, same shut off with the tail on the end even. It’s like I’m looking at mine :slight_smile:

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This is good content. Kudos!

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hahahahaha my husband thinks he is going to install this in the kitchen. why would he? there is a bathroom right beside my grow room! why would I keep hauling gallons of water down the stairs. water lines running beside my room about to get tapped into . he may end up hating me after all this

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have him run the water line into your grow, and into a rain barrel so you can have a constant source of water right there

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the water lines are all exposed in the basement ceiling and the grow room has block walls that separate it from the bathroom that dont go all the way to the ceiling like maybe 4 inches of open space between the 2 rooms. I put that 75 gallon aquarium in the corner I was going to use it for a water source before I found the filter set up. how many gallons does a rain barrel usually carry? I have a floor drain in the center of the room for drainage if flooding were to happen

55 gallons

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