Free water for industrial users

Whenever, on a rainy day, I am driving down through the San Ġwann Industrial Estate's main arterial road and find myself caught right in the middle of a long stretch of flooded thoroughfare, I always ask myself:

How come nobody, from the many surrounding factories, has ever thought of constructing underground reservoirs to catch some of this abundantly flowing water just outside their premises? Would such a construction cost so much that whoever is responsible does not consider it feasible and economical to dig these reservoirs under their own parking grounds and soft areas? Probably these factories are all paying very high water bills. So, what is keeping them from constructing such reservoirs if they know that such an expensive commodity, water, could come in almost for free?