Reaction of aluminium trichloride with water
Aluminum chloride is very soluble in water, according to wikipedia 44-49g/100ml water depending on the temperature, so you shouldn't expect any preciptation. The reaction is very aggresive and exothermic.
Assuming you dont have any buffers or bases in solution when you add $AlCl_3$, the reaction will lower the pH. At a pH lower than 4-ish, $Al^{3+}$ is the most stable cation. Thus, the reaction
$$\ce{AlCl3 + 3H2O -&gt; Al(OH)3 + 3HCl}$$
is pretty accurate. Aluminum hydroxides are decreasingly stable at low pH, as you can see below. Since HCl is formed upon dissolution of $AlCl_3$ you can safely assume that $Al^{3+}$ is the only Al-species present.

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