Not all boat Pex, is Pex

Liberty44140

I am adding a water filter to my galley faucet. I use an RV filter at the dock spogot at the city water outlet but I want to stop carting bottled water to the boat. We put an under sink filter in at our bar at home and it’s been awesome so adding to the boat. On my 342 I had a Brita faucet mounted filter in the galley and it was great but this boats faucet won’t work for that. This filter will feed both the galley and head sinks. Seemed pretty easy to use shark bites on the pex to to attach the 3/8” threaded compression fittings (standard home sink water lines), right? Wrong! The ID of my lines is narrower than standard Home Depot pex so shark bites won’t fit!

off to hardware store and we are really lucky to boat in a major boating community as the guy at the store says “yep, newer boats have standard pex now, older boats use polybutylene, but early to mid 2000s? Looks like Pex but it is 15mm”. Was lucky he stocks parts so I was all set.

so heads up, your pex may not be pex, May be “15mm”…

Willhound

Sharkbite (and it's copies) make a Polybutyl to PEX adapter coupling, so an extra fitting, but allows you to go to PEX for the rest of your fittings. Yes, you were lucky as the straight PB fittings are harder to find, especially away from the coasts.

LaRea

Will the filter feed your ice maker too?

Liberty44140

Will, My tubes are not PB, they are PE just like pex, but 15mm, not standard pex youd find at HD.

LR, no it won’t feed the ice maker. Thought about mounting it in the engine room so that it would feed the entire boat but was concerned about heat. Our city water is very good and I have the dockside filter so I really don’t need it for ice, it’s the straight drinking water that we wanted it for.

Willhound

Liberty44140 said:

Will, My tubes are not PB, they are PE just like pex, but 15mm, not standard pex youd find at HD.

Ahh...sorry. Your first post said Polybutylene. Probably spell correct....

Liberty44140

I did a bad job explaining. Older boats, like 70s and 80s had PB. By early 2000s they moved to PE and it looks like pex, it’s just got a narrower ID that won’t work with shark bites. Based on what I see online it may be known as pex-B 15mm. Anyway just a warning if you’re planning water line work and you’ve got blue and red water lines to double check. There seems to be online availability. 

MH342

Check out whale pumps for plumbing fittings that work with that 15mm tubing. Here is the link to their literature …
https://www.whalepumps.com/marine/resources-library.aspx?Application_listItem_ID=10796

The 15mm was OEM on my last boat and these fittings worked. 

Liberty44140

Ended up working out well. Once I had the right connections for my 15mm pex it all installed in 20 min or less. Will be watching it closely when we turn city water on this spring. Will be nice to have the filtered water in the galley and head sinks: