If you are unable to provide fresh, clean water regularly throughout the day you need to provide an insulated, heated water bowl in order to keep the water from freezing. (ottawahumane.ca)
Another option is to purchase heated water bowls, available at pet stores and online. (spcanevada.org)
During the winter, there are tons of ways to keep water from freezing, like using heated water bowls and shielding the bowls from wind. (alleycat.org)