Brussels Airlines Bae-146-200s

I’ve flown on a BAe 146-200 with Brussels Airlines yesterday, and I got told by the FA that the 146s are leaving the fleet, to be replaced by Avro RJ85s…

Also, getting out of the plane, I noticed a cargo hold door open on the right side in front of the wheel bay, with a hose hanging out of it, and liquid pouring out. What can it have been? Water ? (Note this was the day’s last flight).