There's a big difference between a dam and a pool; the pool is supported by the ground, and even if you bash holes in it, the water still has to find somewhere to go. Also, pools are not typically built from concrete and stainless steel.

The safety requirement here is not "doesn't leak", it's "holds most of the water for 30 days (after which water is not required)". You would have to get an implausibly-large leak, during a situation where nobody can add more water for a month.