I am thinking of placing a 1000L rainwater tank in greenhouse to prevent temperatures inside greenhouse from dropping below 0°C(32°F). The tank is from PE-HD plastic. I am not able to assess how likely it is that the frezzing water damages the tank. Does anyone have any experience with water freezing in rainfall tanks? Does it damage the tank even if you fill only 3/4 of it?

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  • How cold does is get where you are in winter. It will depend on how full the systems will get. If there is not room left for expansion you will have problem will any material. I have to assume the manufacture has them rated to a certain temperature below freezing. I would contact the manufacture if you do not have the manual. Most manuals are found online now a days. Have you searched? – GardenGems Jan 4 at 14:11
  • Thanks! I've contacted manufacturer. Will post an answer once I get it. – sanjihan Jan 4 at 16:18
  • Full would be best as you have more warm mass. – blacksmith37 Jan 4 at 21:12
  • The manufacturer hasn't performed any tests with freezing water. – sanjihan Jan 8 at 23:31

It will tolerate a "little" ice; I think one inch thickness would not be bad. It does not need to freeze solid to break . Once a solid layer forms at the surface and is well attached to the sides, continued freezing expansion will pressurize the water until the tank bursts. Freeze damage of equipment is often NOT where the ice is , but caused by water pressure. The simple solution is an immersion electric heater with a set temperature of about 35 F. Insulation such as Styrofoam panels would also be giant help.

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  • I have about an 3200 L pond . In cold weather I float Styrofoam panels ( 25 to 50 mm thick) on 90% of the surface and add 100 to 200 watts of heat, as needed . This maintains water temperature above 50 F - enough for some types of tropical fish to survive with air temperature below 32F for at least 48 hours. – blacksmith37 Jan 4 at 21:10
  • Thanks for stopping by and giving an interesting insight! I'd like to allow freezing, since freezeing itself if exothermic. – sanjihan Jan 5 at 8:24

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