It’s only a matter of time before a drone takes down a passenger plane

The article is pretty convincing that that won't solve the problem. Eg, "Things can change, though, if drones fly in swarms" and "from a technical perspective a drone can fly 2,000 feet up just as easily as it can fly near the ground".

The tallest fountain is 260 meters/853 feet - https://en.wikipedia.org/wiki/Fountain#The_tallest_fountains... .

As https://en.wikipedia.org/wiki/King_Fahd%27s_Fountain points out, "The water it ejects can reach a speed of 375 km/h (233 mph) and its airborne mass can exceed 16 tonnes (18 short tons)."

So it's going to be very hard to take down a drone at 2,000 with a water cannon, even if the drone is directly over the cannon.