Cooling brakes with water is not an acceptable practice - it can cause distortion and cracking of wheels as well as damage to brakes. Boeing with regard to brake cooling on 747s states that a fine mist of water may be used for cooling but not hoses or as I have seen ,buckets of water being thrown over brakes - this causes thermal shock. AC trucks can provide ambient air for brake cooling but usually there is only one provided so it is time consuming.The best I have seen was at the old Bangkok airport -Don Maung - where individual fans driven by small Honda motors could be positioned at each wheel to suck air through the brake units - very effective. The were brought by the handling company on a trailer but as there were only 8 units they had to be swapped around on a 16 wheel 747. Used them a couple of times when Flight Mech on heavy 747s and was impressed. Never seen such equipment anywhere else.