Although Dong Tianyu didn't pack any water, he did pack five one-liter bottles of high-concentration, edible alcohol.
This had two uses: it could be used to clean wounds, or diluted with water to quench their thirst in place of any other drink.
At a time like this, talking about whether it is healthy or not is pointless. Even if someone were explicitly told it was industrial alcohol, they would still gulp it down to quench their thirst.
It's not that Dong Tianyu was stingy with alcohol. It's just that the cost-performance ratio of alcohol was too low. Cheaper alcohol could potentially be adulterated with drinking alcohol, so it was better to give pure ethanol directly, as it occupies less space.
After packing these items, Dong Tianyu looked at the remaining space in the bag. Based on his parents' sizes, he fetched a few sets of thermal clothing from the Black Tortoise Warehouse.