How to make a mini pond<br>Find a suitable waterproof container or basin. It should measure about 20 centimeter (7.9 in) long and 20 centimeter (7.9 in) wide and 10 centimeter (3.9 in) deep. Clean the container under the running water for 1 minute.

Based on that paragraph can we conclude that this sentence is true?
The container should be a solid material.