The reason for putting RV antifreeze down the drains is to protect the p-traps from freezing. This ensures all the water is drained out of them. The antifreeze displaces the water.
However, one year on my last TT, I missed the p-trap in the kitchen sink. And yes, it froze and I had to replace it in the Spring when it leaked all over.
It was right then I realized, I could just pull the p-traps and dump them out into a bucket and DONE! Ever since then, that's how I took care of the p-traps. Only exception was the bathtub in one trailer and a shower in another, and I did have access to remove it. But it was just a bit of too much work to remove it, so I just dumped the "pink" down the drain. Never had another freeze up again.
