No metal except MAYBE bronze is recommended for use in sanitation systems 'cuz urine is so corrosive that it'll eat through it.

I'm not a fan of Jabsco y-valves either. The best ones--including Whale--have a "barrel" inside that the handle rotates...the Jabsco otoh just has a little "gate" that the handle swings to block one side or the other. It's pretty flimsy...I've seen it jammed by a water melon seed, then broken in an attempt to free it.

My advice: put new seals in the Whale.