At this time of year it,s dieing back for the winter, so wont need as much water, yellowing of the leaves is quite normal.

If its indoors, and you mean Zantedeschia, they don't like to dry out - but yellow leaves can either mean too little or too much water. If the yellow leaves are soggy looking, that's too much water - if they're just going yellow and then turn crispy brown, not enough water. If your Zantedeschia is a hardy, outdoor form such as 'Crowborough' yellowing of the leaves is a precursor to its dying back down for the winter.