The fresh water tank will have a drain valve , should be above the floor where the water is coming out. Other water may be coming from the water system's "low point drains " , one for the hot water lines , the other for the cold, also above the floor where the water is coming out.
BTW: Welcome to iRV2.
99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.