Alum is generally used in water tanks to settle down solid impurities. Since it contains aluminium I suspect it to be toxic to humans. So are there any safe chemicals to clean large overhead tanks without removing the water or doing much effort. I am asking about solid impurities and not disinfection .


1 Answer 1


Aluminum is remarkable safe for human consumption, also considering that it is present in high concentration essentially everywhere, and it is not known to have any significant specific biological roles. Wikipedia happens to have a nice well researcher section on aluminum's possible effects on human and animal health: Aluminium: health concerns. Alum is also routinely added to water in low concentrations for elimination of solid particulate, as you mentioned.

My main concern for your application is the fact that typical methods of water purification from solid particulate, just like addition of alum, will tend to form flocs in your water tank that will then need to be removed! Depending whether this scum will float on top of the water, or sink to the bottom of the tank, the removal may be more or less easy, also depending on what kind of access you have to this tank. I doubt if any of those solutions would count as not "doing much effort"...

  • $\begingroup$ Thanks , but Al is toxic even the article says so, and Alum has been recently implicated in A new study, dated Feb 5 2015, links the brain translocation of alum particles to a Trojan horse mechanism, that obeys to CCL2, signaling the major inflammatory monocyte chemoattractant.[94] $\endgroup$
    – chem101
    Commented May 31, 2015 at 17:14
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    $\begingroup$ Hmm, the fact that one study hypothesizes that injectable alum may be biopersistent is a far cry from showing that aluminum is toxic. The article explicitly says that "Aluminium salts are remarkably nontoxic, aluminium sulfate having an LD50 of 6207 mg/kg (oral, mouse), which corresponds to 500 grams for an 80 kg (180 lb) person." This is from Ullman's Encyclopedia of Chemical Technology. $\endgroup$
    – MarcoB
    Commented May 31, 2015 at 17:41
  • $\begingroup$ Marco B so if a peice of a kilo solid piece of alumif dropped in over head tank would be sufficient to clean. Tge water and non toxic to us and children ? $\endgroup$
    – user83704
    Commented Sep 13, 2019 at 8:25

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