Ok, here is the anti-wife discussion
When the SHTF 15 thousand gallons of water is not much good, maybe 2-3 months before it is either taken or contaminated.
The concept behind prepping is to become self sufficient so you need to have a reliable source of water for YEARS not weeks. So if the wife is saying lets put in a pool, its a good prep then sorry she is wrong.
If you have a pool then it is a good prep but only for a very short term.
Water WILL be the number 1 concern if the SHTF so have a infinite source and a way to make it drinkable. The only reliable way is a well and a filtration system, open sources will quickly become unreliable.