As you know The Mexican state grants a mining concession (a permit to explore and exploit minerals in the subsoil) so I have 3 gold mines in store but no idea how to sell it, any ideas?...

Over time minerals in the water build up in the bottom and cause the tanks to rust from the inside out and decrease the life of the appliance.I worked for an appliance company all throughout high school, you'd be amazed how old some of the units were we pulled/replaced for customers.

It has the downsides of being somewhat invested in oil and being vulnerable to hurricanes, but from what I've read both of these downsides are mitigated by Houston having a pretty broad job market nowadays, and buying homes outside of flood zones.

I remember back in the early 1980s the mineral rights under my house, as well as all the others in the development, was sold or leased to a wildcatter who “slant” drilled for gas under our property.

That coupled with the supply chain problems and the Ukraine-Russian war effect upon grain prices and oil prices suggest that we will be in for a bumpy ride for a bit. 

For example, here in Northern NJ, it's common to inspect for in-ground oil tanks during the inspection process.Fourth, the agent needs to provide excellent client service to out of state clients. 

But oh, let's listen to the Republican crowd who is basically bought and paid for by the insurance companies, oil companies and other large corps that are killing you off in other ways for your dollar.

We'll know what BP is, however to most of the world it's a big oil company that had a huge spill last year.

The older victorians you have major issues because of age.Knob and tube wiring,galvanzied pipes,foundation issues,asbestos,oil heating tanks,mold,radon,etc.How many other properties are in your name??

I've heard theories about minerals in the water, and poorly done joints causing micro-currents which in turn cause excess erosion at those point of the pipe.Given that it's happened multiple times I'd be nervous about leaving the rest in the house, personally In my mind I'd be making plans to do just as you suggested - replacing everything with PEX.