That looks like PVC pipe (unusual in an RV), but that elbow can be replaced with any type that fits the pipe. They are sometimes called elbow unions because they are either compression fittings or "push-to-fit" types.
Here's a couple that ought to work:
Or if that white tube is pex that just looks like PVC, any push-to-fit pex fitting would work. Flair-It makes an easy to use one.