Mare a Mare Nord Variant Supplies?

Can anyone advise on how well supplied (food-wise) one needs to be on the Nord a Nord Variant segment? From satellite maps, it seems (if going from West to East) the last major populated stop is Guagno.

So should one carry 3-4 days worth of supplies to get from Guagno to Vivario?

Also, what's the water supply situation like along the route? Will a filter and tablets do the trick?

Thanks for your input!