When you are running short on wine and the Becher (Kiddush cup) isn’t full…



If one doesn’t have enough wine to fill up the kiddush cup, can water be added? (Speaking about regular wines which could be are already heavily diluted) or is there another alternative such as chamar medina, challah, etc.?



One may only add water to the extent that the wine – or grape juice – can still be drunk as wine and served to guests that way.

See here for more conditions:

Diluting the Seder Wine due to Health Concerns

And if not, then is it better just to make kiddush without a full cup,

You can add something else to the cup, like a fruit, or an ice cube, so that it should be full, provided it has at least a Revi’is of wine.

ראה אדה״ז קפב, ד. ברכת הבית  מז בשע״ב ב. משנ״ב קפב, לב.

Where the above is not possible, it’s still better to use a Revi’is wine in a cup which isn’t full than using chamar medina.

אדה״ז רצו, ט.