Abstract: The invention presented herein provides an improved method for controlling the blowdown of recirculating water for an industrial cooling system or the like, in direct proportion to the heat load on refrigeration systems. A temperature probe is positioned in the recirculating water which is in communication with a blowdown valve. As the heat load on the system increases the temperature of the cooling water increases and the blowdown valve is then regulated to release more of the circulating water. Additional makeup water and chemicals may be also supplied to the cooling system to maintain a proper chemical balance.In the preferred embodiment of the invention the probe is positioned between the refrigerant condenser and the cooling tower in the circulating water system. Appropriate chemical feed systems and makeup water can be regulated to function in relation to the amount of blowdown to insure that the desired chemical balance is maintained.