Consider a reasonable capacity for a water bottle.<br><br>
&bull; 500 litres is far too much (the size of a bathtub).<br>
&bull; 500 m&ell; (millilitres) = 500 cm&sup3; (same volume, different unit).<br>
&bull; 500 cm&sup3; is about half a litre -- a reasonable water bottle size.<br><br>
Final Answer: cm&sup3;