Putting 700 gallons of water on that inferno is the equivalent of pissing in the ocean. Yes in theory, any amount of water would lower the temperature but it would be a minuscule amount.
Perhaps the actual number is 700 gallons per minute. Although I they were probably no more accurate on the metric to imperial conversion.
Yes, I thought it sounded like a small amount, too. Possibly something lost in translation. The “big picture” is that it did an amazing job.