In our company we do fuel water drains on our A330 every weekly check. A/C is pre-fuelled with about 10T of "warm" fuel and left to stand for six hours to let the ice melt.
Then the tanks are drained. We get gallons of water out of them.
Other than the weekly check the A/C never cools down or the ice in the tanks melt, max 2hr transits. If it wasn't for the fact we needed 6hrs ground time for it to stand, OPs would continue to fly it. We use this valuable ground time to catch up on maintenance and try to clear a few B's.