How big is the room? Can't you get one of those big platic containers with the little tap on the front (can't think of the word for them now!!!)
Beer keg ?
Put a beer brewing barrel one with a tap on some wall brackets, go to your local caravaning centre and buy a little round caravan sink and sit it on top of another beer brewing barrel.
Water from the top one into the bottom one, you have running water.
Thats the way I did my old loft darkroom.
Both barrels could also be obtained from a large camping outlet.
am with ya
but 30l is 30kg and balls to lifting that high enough to work
Place it where you want and fill it there with a hose or just put in as much as you will need.