Good question EMT.
Most people don't know (and a small group on this forum don't care either) that there is a Uniform Building Code that has been adopted by most states. In many states, there are county/city building and safety bureaus that enforce the state code and add wrinkles that are local.
The concept tramples over protestations that a person's home is his kingdom.
Most states do have mandatory building codes, but there are still 15 states where the existence of codes is a matter of local jurisdiction. Often it is the larger cities that opt for control of building practice, while the the more rural areas are freer. This is true in Alabama, Arkansas, Hawaii, Michigan, Missouri, North Dakota, South Dakota, and Wyoming.
Some states have just a few counties that have yet to establish code requirements. In Arizona there is only one such county (Greenlee); in California there are three (Mendocino, Humbolt, and Nevada) that have adopted the liberal “Limited Density Rural Dwellings” program; Colorado has 15 open counties ); Iowa has eight free counties; Mississippi is mostly free, except for coastal areas where wind and flood codes are enforced.
So let's speak about the real world. Each street, every block, every small community has its inspector general. The Inspector General may be a bored housewife, a retired senior, a guy trying to sell his house. The Inspector General has many disguises. He spots YOU.
YOU have a noisy baby. YOU insist on parking the car on the front lawn and running your lawn mower at 6 am because you have to do something important at 9 am every Saturday morning and 6 am is the only time that you can mow your lawn. YOU let your dogs run free because God dictated that dogs should run free. Well, your neighbor gets pissed off at you and turns you in.
One neighbor didn't like the 6 kid legal day care across the street. When the illegal house addition was finished, he called the authorities.
One neighbor did not like the trash piling up in the next neighbor's yard and called Public Health who would inspect and issue citations every single year. It didn't matter that the first neighbor ran a crack house. The house was sold after the local cops said it could be confiscated and after a "girlfriend" tried to stuff the newborn down the toilet. Honest to God, I could not make this up.
The neighbor with the non running cars last licensed in 1985 and 1992 routinely turns in his neighbors too. Doesn't matter that he also makes cooing noises at 6 am every day to his two dogs!
So EMT, go ahead and put in whatever tank/underground shelter you want. Most people also cross their fingers when they do it.