plastic taste in drinking water

Maybe it is the hose you are using to supply the trailer.

Pretty sure it is from the rv anti freeze as it was fine before.Heard vinegar can work but just got home.

I also have never had an off-flavor in the water, and I sometimes leave my tank filled for a month. Don't think the flavor is from your tank or pipes. My grandmother's water tasted like plastic, but she lived in Cleveland. None of her pipes were plastic. :D

Are you sure the taste is plastic? Could it be from the RV anti freeze? I've never had any off flavor tastes from my tank. However, I never used RV anti freeze either.

I'd suggest to put some baking soda or peroxide into the system and flush it out thoroughly a couple more times. Make sure all pipes and valves are allowed to flush completely. I doubt you are tasting "plastic" as you describe it from the plumbing because the tank material is food grade polyethylene and PEX is inert to the water. It's more likely that you are tasting the residual antifreeze that was in the system or water from another source that had acquired a taste.

Hi, I have a separate small tap at my kitchen sink that has a quality nline filter under the counter that we use for drinking or making hot beverages. It works well.
I find when I first fill the tank from home the water is fine but after several days the water starts to taste a little like the plastic as well.
Lots of RV folks use a proper RV inline filter for the whole water system.