Question: One night during Ramadaan, I was sleeping at my cousin’s home, who is my brother-in-law as well. We were in the desert where there were no mosques nearby, and the village is far away from us. I slept after having my Suhoor (pre-dawn meal before the Fast), and woke up suddenly, asking my wife: “What is the time right now?”
She replied: “It is 4 o’clock.”
However, the Fast starts at a quarter to five. In other words, only a short time was left; so, I slept again and when I woke up, I thought I did not sleep for a long time. In addition, my wife put a glass of water near me while I was asleep, so that I could drink before the time of Imsaak (time of day that marks the beginning of the Fast).
I said to myself: “There is enough time left,” and then I drank. After going out of the tent, I found the dawn had broken but the sun had not risen yet, as it was approximately a quarter past five because I did not have a watch at the time. What is the ruling?
Answer: It is obligatory on you to make up for the day on which you drank after daybreak. In other words, your Fast was invalidated... read more here.