Spectra Watermakers are rated to work in near freezing water. The one exception is the Ventura 200T which is rated at 50 degrees Fahrenheit. Many customers have used our watermakers in arctic waters with much satisfaction. You can read about S/V Kotik in Antarctica on our blog here: S/V Kotik in Antarctica. All of our systems are designed to be inherently self-balancing, so at the water temperature drops, there is no need to make any adjustments to your watermaker at all. Just start the system up and enjoy the water at its full rated capacity.