Wikipedia states it well,
No ethnographic studies have shown that any present or past society has used barter without any other medium of exchange or measurement, and anthropologists have found no evidence that money emerged from barter.
In other words, people don’t barter unless they are used to money, but don’t have it.
The article isn’t clear enough about this. This pump is nowhere close to the fires, and the water coming out of the pump doesn’t get anywhere close to the fires, either.
The purpose of the pumps is to take water from rivers and send it to wealthy farmers. The farmers didn’t even need the water, anyway, this time of year.