I purchased an underink water filter: KOHLER Aquifer Under-Sink Double Cartridge Water Filtration System

I was using the plastic connection that came with it:

enter image description here

Connected like so: enter image description here

The top connects to my faucet (plastic male to female connection), and the blue plastic hose push connects to the KOHLER water filter which connects to my fridge's water line

The fitting is leaking where it threads into the water valve (plastic female to male connection). I took the fitting to lowes/home depot and tried to attach it to newer valves but it would always spin in place when trying to connect. I suppose the threads got damaged.

Please, how can I combine a brass fitting to replace this setup? I don't mind having to use several adapters

In the photographs of the water filter I noticed they used an adapter as well:

enter image description here

The closest thing I could find in lowes was a male to push adapter: enter image description here

This is my water valve after some disconnections: enter image description here

I am pretty sure its 3/4 inch for all connections (this may be incorrect according to manual stating 3/8 inch water supply connection.

The OD of the blue plastic tube is 3/4 though the push connection is labled 3/8. Could you please point me to the parts I need to fix this issue? I currently have turned off my cold water supply because the leak is really bad.

Thank you

  • this is a compression fitting
    – Traveler
    Oct 5, 2023 at 3:28
  • The push-connect fitting is going to be the problem here. Can you please measure and report the OD (outside diameter) of the blue plastic tubing, in inches? Oct 5, 2023 at 3:54
  • @JimmyFix-it Okay, the OD of the blue plastic tubing is 3/4 inches. the manual says: This system connects to a 3/8″ (9/16″-24 UNEF-2A) compression connection. Special fittings may need to be purchased to accommodate other connections Oct 5, 2023 at 4:14
  • I couldn't edit my comment above. I measured by placing the tube on measuring tape. However 3/4inch seems wrong for an OD because that black reducing coupler in the photograph is a 3/8inch OD to 1/4inch OD (assuming the amazon description is 100% accurate here) So that means the blue plastic tube is actually 3/8? Sorry Oct 5, 2023 at 5:06
  • Kohler's service website: kohler.com/en/products/water-filtration/shop-water-filtration/…. They sell a brass tee for 14 USD: kohler.com/en/support/find-a-service-part/shop-parts/…. Typically I try to avoid mating female plastic threads to male metal threads, as I always break something. So I like your male threaded connector (as long as it actually fits your hose).
    – popham
    Oct 5, 2023 at 21:30

1 Answer 1


I solved it using an adapter tee: enter image description here

and a 3/8 Inch Compression Female Connector to Push to Connect enter image description here

Thanks everyone

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