The Blessed Month of 
Ramadhan is the Month of Allah. This attribution of the month to Allah was also mentioned by the Holy Prophet (s) in his famous Sha’baniyyah Sermon, “O people! Surely the Month of Allah, with all its blessings and mercy and opportunities of attaining forgiveness, has approached you.” 
Just as objects require a clean every once in a while, the soul of a human being requires the same, as it becomes darkened by the effects of sin. Just as water is not only pure but also a purifier and cleans dirt off objects, this month is not only pure and blessed but also purifies the human soul and heart from sins and their effects when they fast and worship Allah (swt) in it.