There are sometimes bubbles and foam in water. This is a sinful reaction water had to accept from Indra in exchange for his blessings that water would increase the volume of substances with which it was mixed. (Srimad Bhagavatam 6.9.10). In the summary to this chapter, Srila Prabhupada wrote, “Since water was also infested with sinful reactions, when bubbles appear in water it cannot be used for any purpose.”