An area in which myriad studies have been conducted regarding aluminum as an environmental factor is the correlation between the number of diagnosed AD cases and the aluminum levels in public drinking water. The reason aluminum is added to drinking water is most commonly as a clearing agent¹. The amount of aluminum present in drinking water has been recommended to be below 200 micrograms per liter by the World Health Organization.

In a study conducted by D.R.C. McLachlan and colleagues, it was found that a relationship did exist between the number of diagnosed AD cases and the level of aluminum present in the drinking water supply. This study concluded that between 15,180 and 26,910 of the estimated 66,000 to 117,000 cases of AD might have been prevented if the aluminum concentration in the municipal water supply had been kept below 100 micrograms per liter². A similar study performed by H. Jacqmin and associates using different variables showed no significant effect for aluminum in drinking water when pH was not included in the experiment model, but showed a small relationship between aluminum and AD when pH was also taken into consideration³.

Several other studies have shown no relationship to exist between AD and aluminum, for example, those lead by DJ Wood and A. Wettstein^4,5. Their conclusion, that the silicon in the water reacted with the aluminum to reduce the neurotoxicity presented by aluminum, concurs with the previous conclusion by Birchell et al.. Birchell et al. suggested in his report that the inverse relationship between soluble aluminum and soluble silicon shows that maintaining a constant level of approximately 3 milligrams per liter of soluble silicon in drinking water would be enough to protect the population against neurotoxic effects of the absorption of all forms of aluminum in the diet⁶.