Alum

[Lassie]

My uncle puts alum in his water tank, and I am puzzled. What is the role of alum in the water tank? Does it kill bacteria or clean the water?

[fresh]

A lot of commercial industries use alum to purify drinking water. Alum works because it can separate the surface charge known as the double layer. It is a pretty complicated explanation I do not fully understand but I do know it works.

[Pat]

A lot of commercial industries use alum to purify drinking water. Alum works because it can separate the surface charge known as the double layer. It is a pretty complicated explanation I do not fully understand but I do know it works.

Alum is an agglutinating agent (causes non dissolved impurities to clump together into larger sizes to be more easily filtered out.) Alum is used in pond clearing where the agglutinated impurities just sink to the bottom leaving the water much more clear. It can also cause you to make a really awful face if you taste it!!! (Lick a styptic pencil.)

Pat