[header] How to supercool water [title] Gather the necessary materials. [step] For this method, you will need salt, purified water, a small clean glass or plastic cup, a large bowl, and ice. If you have a thermometer it would also be useful, but not necessary. 
[substeps] Make sure your glass is very clean; any impurities can cause the water to crystallize into ice before supercooling occurs. The bowl must be large enough to contain the glass and enough ice to submerge the glass.