If you can find a wide-mouth pet waterer you can use that. Otherwise you can easily make one in just minutes (see last photo).
1) FILL the container with ice cubes, NO WATER. 2) Assemble. 3) Cover the container with insulation (Old sock shown).. or wrap with towels and secure. Keep it out of sun.
IT SHOULD last for several hours or much longer with more insulation. .
. . IF they don't drink it fast enough, it will eventually all get warm. Or you can drill a very tiny hole or notch in the bowl just below water level so there will be a continuous flow of cold water.
(LATER - UPDATE) - The ice in this very small one lasted 4-1/2 hours...stayed cool another 1/2 hour. A one gallon sized container (last picture) should last 6-8 hours or more...??
(Photo below) Use any wide-mouth sealable container of any size (fairly rigid plastic). Drill 1/4" hole on side of container 1" from the top. 1" will be the ice water depth, or 2", or 1/2". Drill location of hole depending on the pet size. Fill with ice cubes (NO water, water melts the ice cubes faster). Invert container into a large pan. The ice will melt and discharge ice water for HOURS for your pet. Wrap the container in insulation (or a towel, or ??) to make the ice last longer. Depending on your pet, you may have to secure the container so they won't knock it over... a bungee cord around the container AND pan should do the job.
IF they don't drink it fast enough, it will eventually all get warm. Or you can cut a small notch or hole in the pan 1/8" below the water level so there will be a continuous flow of cold water in. . . . and the surplus water out at the same rate as the ice melts.
