Architectural detail: Rain gutters leading to watering cans

A while ago, I saw this:

[Max Levy via desire to inspire]

I've seen other rain-reuse products, but this version was much more attractive than a big plastic rain barrel.  However, considering how much it has rained in Seattle this week, I suspect those charming watering cans would not be able to handle the volume here.  Curious to know the watering-can requirement for our house, I did some internet sleuthing and it brought me to this equation:

Rain Caught (gallons) = Footprint to downspout (ft²) x rain event (in) x 0.6
[Equation originally found here]

So, for the roof over our living/dining room, it works out like this:

Footprint of roof = 25' * 12' = 300 sqft
Rain event (I assume this refers to the amount collected in one shower.  In our case, I supposed that we would not check on the watering cans for the month of January, which seemed reasonable.) = 5.4"
Multiplier = 0.6 (One inch of rain falling on one square foot yields about 0.6 gallons of water)

300 * 5.4 * 0.6 = 972 gallons

Holy smokes!  So.  If I used this watering can from Ikea, that would mean I would need 748 watering cans to hold all the water.  Even if I weren't lazy and emptied the watering cans every day, I'd still need  around 24 of them.  At those quantities, the wall would probably have to be re-engineered just to carry the extra weight.*

In conclusion, this is not a practical solution for Seattlites.  But I haven't abandoned the idea completely. I think it could be quite lovely as a decorative detail if it were combined with a cistern to carry the overflow.  Especially if the watering cans could be hung at an angle so they were 'watering' the cistern.  Something like this:

*With 24 watering cans, it would be about 261 lbs. of water when they're full.  The watering cans themselves would add and extra 48 lbs.  So the wall might be okay weight-wise, but there would have to be extra support at the stress points.