Whatever breaks the wudu breaks the tayammum. Looking at water breaks the tayammum. Someone who did tayammum and prayed, then found water while he is [still] in the time of prayer or has exited the time, then there is no repetition [of the prayer] upon him, for the tayammum is one of the two purifications. So, he is to do wudu for another prayer. There is no harm that the man should pray all of the prayer of the night and day with a single wudu so long as did not have a hadath (something that breaks the wudu). Likewise is the person with tayammum so long as he did not have a hadath or come upon water.