Is it permissible to perform Tayammum if water is cut off for a short period (approximately one hour)?

Those who lack water fall into three categories:

1. One who knows or strongly believes they will not be able to find water: It is recommended for them to perform tayammum (definition) and pray at the beginning of the time, so as to attain its virtue.

2. One who is doubtful about the availability of water: They should perform tayammum in the middle of the time, meaning at the end of what is considered "the early part of the time," and delay the prayer hoping to find water, unless they fear missing the virtue of the early time.

3. One who knows or strongly believes water will be available at the end of the time: They should delay the prayer to attain the agreed-upon virtue of water, as it is more important than the virtue of the early time.

Some scholars hold that delaying is obligatory if one is certain water will be available at the end of the time, because ablution (wudu') is the original and more complete purification. Effort must be expended to acquire water before resorting to tayammum.