The proper way to water cool a DC glass laser is with a water chiller. A chiller is essentially a combination of a refrigeration device and a pump that recirculates water around the laser to keep it at a constant temperature.
Note that glass lasers can be damaged by routine handling or thermal shock from an interruption in water cooling. If no cooling flow is provided to the laser, the glass container will break, resulting in a non-functional laser that will need to be replaced. As a result, the service life of DC glass lasers remains limited and is commonly measured in months of operation.
-Manny Oropeza, Universal Laser Systems