Our '99 Xplorer 230 xlwt has the tank drain valve on the tank where the supply line leaves the tank. In ours, the tank is under the driver's side bed, just rear of the bathroom, where the pump is mounted. There is also a drain in the same compartment for the bath sink faucet. And two drains (hot & cold) in the cabinet under the kitchen sink. In ours, these are the only drains needed because the hot water tank will drain when these others are open and faucets are opened.