Another simple and effective idea... but is there a tap in the back of the chair??
And to harvest thru all monsoon season, wonder how many chairs will be needed.....
hmm.... now I have my doubts about the effectiveness of this !

thats is really an impressive idea for harvesting rainwater and can be fruitful if hilly areas.

Yeah.....me too wondering about how to get the chair water the greens. but then i assumed that its the same hose that can be taken off the parasol and directed to the the plants instead.

But what about the number of chairs required to store all the rainwater throughout the monsoon season? That can be a problem.
The chairs may be coming in different sizes and capacities, but like Vikas said, if it is to be used in hilly areas, which usually gets heavy rainfall 2 or 3 chairs will get filled up pretty fast and most other water will have to be wasted (viz. cannot be harvested), unless you buy more chairs. But that would become impractical after some point... in comparison, say having a large water storage tanks can harvest much more water throughout the season.
Just my thoughts...

I get your point Manish but then this is a concept to store more water over and above the storage tanks. Also it intends to beautify the garden with such water-storing furniture. Instead of placing basic metal or plastic chairs, this is a better option.

Oh yes, for additional storage, this is a great option. And it surely beats the plastic garden chairs in every way.. looks and also use.