Does not drinking from the Well of Zamzam after performing Tawaf and Sa'i affect the validity of 'Umrah?

There is nothing upon you, and your 'Umrah is valid, because drinking from the Zamzam well after the two rak'ahs of Tawaf is not a pillar or an obligation of 'Umrah; rather, it is a recommended act. So, whoever does it, it is good, and whoever leaves it, there is nothing upon him, whether intentionally or forgetfully.