You should have at least three of them, kitchen sink/dish washer, shower, and bathroom sink/sinks. Don't know on the washer if it might have one or depend on the one down stream. If you can get access to them, they're easy to remove and check in the internal sleeve hasn't been torn or damaged in some way.
Michelle & Ann
2018 Chevy 3500HD Crew Cab High Country DRW, D/A, 2016 RW39MB, Dual ACs, Auto Level, Auto Sat Dish, Stack W/D, King Sleep #, 17.5" Sailuns w/Disc, MORryde IS & Pin, Comfort Ride Hitch, 5.5 Onan, Res Fridge & Induction Cook Top