Abstract: Provided are methods for substantially removing organic substances from an aqueous solution, wherein the aqueous solution is contacted with a synthetic hydrated calcium silicate. Components that can be removed from aqueous solution include bacterial, plant, algal and fungal components. Exemplary components include endotoxins. The aqueous solution comprises, for example, water, a chemically buffered solution, a pharmaceutical solution, a solution comprising a nutritional supplement, a culture medium, or a growth medium. Other examples include pharmaceutical compendial water and non-compendial water. In one embodiment of the method, the pH of the aqueous solution is maintained at a selected pH to promote the separation, for example, about pH 5.5 to 9.5, or, e.g., about pH 5.5 to 7.5.