Depending on which model Gold that you have, the switch for the water pump should be around where tank level gauges are. the switch should have a red light that comes on when the switch is on (if I remember correctly).
The drain for the fresh water should be a underneath between the axles, my 97 Ideal was there anyways, to flush it out, I would put some chlorinated water in the fresh water tank fill, then let it drain out.
If you can't find the switch or drain, call Alfateers, they bought all the blueprints and left over parts from Leisure when they went out of business.
03 Silverado cclb 3500 drw, D/A, Reese 22k hitch
07 Alfa SeeYa Gold 30RL,2 slides,power everything