I plugged my DI vessel round the wrong way today. Mains water attached to OUT port and IN port going from DI vessel to van tank. I found a whole lot of resin in the bottom the tank so I ended up having to remove it from the van, flush it out, put it back in the van & refill. What a pain! At least I have a translucent tank otherwise I might not have noticed my error.
Anyway lesson learned...