94 Fleetwood Elkhorn water leak!!! Help

So I just picked up this 94 Fleetwood Alcorn slime camper for pick up I started to fill the freshwater tanks with water just to test them out I heard water coming out of the back of the camper above the rear bumper there’s this little white or plastic piece with a hole in it the waters coming out of there I’m not sure what that is or have a plug in it I’ll post a picture of it but if anybody could help me that would be great thank you for your help I try to post a picture but apparently you can’t do that I’m here if you respond to my ad I can definitely send it to you