There isn't an easy way to plumb water to the place where we need the cooling (the living room, which is also my home office), so in order to actually use the evaporative cooler, we have to fill it with water manually. Here's what it looked like dry after having sat for a week with the multiple coats of paint having had plenty of time to cure.
And here it is full of water, although it's sort of hard to see in the picture. The bucket holds between 9-11 liters of water, and it takes three bucket-loads to fill the cooler pan to within 1-2 cm of the rim.
With pan full and the cover replaced, I turned the pump on. The way this kind of cooler works is that you should run the pump for a while to pump water up to the top where it percolates through the blue pads. The pump made funny noises initially, but once it stopped sucking air, everything was fine. Once the pads were well saturated, I turned on the fan. Success! Lots of cool air, evaporating in the low humidity and providing immediate relief from the heat.
We have to keep a couple of windows open in order for this to work properly. Otherwise, you get too much humidity and not enough evaporation. Also, once the outside air temperatures get above body temperature (37°C), I find that the cooling effect tends to trail off. It's not perfect, but it's also a lot less expensive than a big home AC system would be, as in one fewer zero in the cost.