The question is not very specific. There are many kinds of water tankers. A water tanker truck, of the largest 18 wheeler kind, can carry about 30 tons of water. Which is about 8000 gallons.
20 tons of plain water is 4,796.2 gallons.
About 36,014 gallons.
About 12,965.2 gallons.
Approximately 22 tons.
2,940 US gallons of water weighs about 11.14 metric tons.
13,094 gallons of plain water weighs 55.51 long tons.
50,000 metric tons of plain water would be 13,217,162.1US gallons.
aprox 21.04 tons
A gallon of water is estimated to weigh 8.34 pounds. 21 tons divided by 8.34 pounds = 5035.97122 gallons of water.
That depends on what kind of substance is in the gallons.-- If they're full of water, then they weigh about 126.19 tons. (rounded)-- If the gallons are empty, then their weight is zero.