Need Plumbing Assistance

Most water lines are 1/2".

What is the standard size for the blue PEX found in most travel trailers?

If that fitting is rated for PEX, then it should work, assuming it is the correct size thread. Shark Bite, Gator Bite, (and Lowes has it's own house brand now) are all quick connect PEX fittings.

Great information, thank you very much.

Is the fitting on the left what I am looking for? I have not been able to find a fitting with a shut-off valve which I would rather have.

You can go to any of the big-box stores and get a "Shark-bite" fitting that will attach to the cut pipe and have the female threaded end to attach to the toilet's male threads.

You can also install a valve into the supply run that will permit you to turn off the water to the toilet. That may be something you wish to have should you have a problem with the toilet and need to work on it or replace it. With a valve, you don't need to shut down the water supply to the rest of the trailer.

If you plan to replace more of your plumbing fixtures or anticipate modifying other supply lines, you can forgo the easy Shark-bite fitting and buy the necessary crimping tool and crimp rings to attach all manner of plumbing fittings. For a one-off job, the Sharkbite fittings are hard to beat.

Thank you for the reply. How does the fitting attach to the line after I cut it? The blue hose is pretty tough. Is it some special type of clamp? The attachment will include the part that screws on to the threads of the toilet?

simple fix, cut the fitting off, take it with you to Lowes and get a new fitting, and resize the hose. The fittings are basically the same as home fixture connectors. Make sure you turn the water off!