What is the validity of Zakat that was disbursed through a charity that distributes Zakat funds to debtors and for the marriage of poor families, and sometimes delivers water to poor homes, with the possibility of handing over the money in cash or converting it into in-kind aid with the approval of the poor, and is it better to deliver future Zakat manually to the poor?

The debtor (gharim) and the poor person unable to marry are among those eligible to receive zakat. It is permissible to spend zakat to provide water to the homes of the poor with their consent. Your zakat is valid, but if it becomes clear that the charity spent the zakat for purposes other than its designated channels, then you are obligated to re-distribute it, and you have the right to claim it back from the charity.