Water is the medium which acts to carry the energies once charged with VK, so until you don’t consume the whole water, energy still remains within water. So there is no waiting required. There is no need to recharge the same water.
When you place a direct request to VK to send energy to a particular energy receiver and then keep it aside, VK sends energy to that particular energy receiver directly . At the same time the receiver is also using the energy. The supply of energy should be balanced with the requirement of receiver, so it is advised to keep VK aside to allow VK to send energy.
30 min is the maximum time VK works on auto healing mode.
You can break the request in between if you wish in case of emergency or critical situation or when the wish is fulfilled before 30 min.
To understand more, please read this post by Sharat Sir
https://forum.litairian.com/discussion/554/what-to-do-after-placing-a-direct-request-to-vk#latest