A:Answer The Intex - Portable Inflatable Hot Tub, item 28441E, can be installed indoor or outdoor. If installed and left outside, make sure the temperature is not lower than 39°F (4°C) . The water provided inside of the spa must be higher than 39°F (4°C), so the water inside of the circulation system will not frozen. We hope this information is helpful and if you need further assistance please call our Service Center at 1-800-234-6839.