I needed to replace leaking water drain line caps on my 2014 Keystone Bullet. The drain lines are Red and Blue. That means they are Pex. Only Pex parts will work. After some research I located 1/2" Qest Pex caps at Fergusons Plumbing supply. The 1/2" plumbing caps at the big box stores do not work.

Some drain lines are terminated with 1/2" threaded plugs, some with caps, and some with more convenient to use valves. Those 1/2" Qest may work in this situation but be aware that in general Qest piping that has long since been replaced by PEX in recreational vehicle manufacturing is sized slightly differently and in some cases won't work. For example, if you were to use a 1/2" Sharkbite fitting designed for use on PEX you'd probably find it would leak if used on Qest pipe.

I put plumbers tape on the threads. Problem solved atleast on mine

I cut the pex lines and used "Watts" (similar to shark bite) push on valves..no more caps for me

I was looking for a solution to this also. I have a keystone TT and have the same caps you speak of. I like the watts solution shown above. I always seem to drop or misplace the caps.

Bucky Badger wrote:I cut the pex lines and used "Watts" (similar to shark bite) push on valves..no more caps for meThere no need to cut the PEX at all ... just buy a valve with a threaded end of the appropriate diameter & sex to match the existing termination on your low point drain lines. This one would screw directly into trailer's such as mine that use threaded plugs to seal the low point drain lines ...... but female versions are also available that would screw on to a capped low point drain line.

Drain line caps | Good Sam Community

ZeeLet50
Explorer
Mar 16, 2017
I was looking for a solution to this also. I have a keystone TT and have the same caps you speak of. I like the watts solution shown above. I always seem to drop or misplace the caps.
Bucky_Badger
Explorer
Mar 15, 2017
I cut the pex lines and used "Watts" (similar to shark bite) push on valves..no more caps for me
Oasisbob
Explorer
Mar 15, 2017
I put plumbers tape on the threads. Problem solved atleast on mine
SoundGuy
Explorer
Mar 15, 2017
Some drain lines are terminated with 1/2" threaded plugs, some with caps, and some with more convenient to use valves. Those 1/2" Qest may work in this situation but be aware that in general Qest piping that has long since been replaced by PEX in recreational vehicle manufacturing is sized slightly differently and in some cases won't work. For example, if you were to use a 1/2" Sharkbite fitting designed for use on PEX you'd probably find it would leak if used on Qest pipe.

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Drain line caps

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