[pinkythepig]

The natural gas genny portion exists, the water one does not. The water one doesn't exist for two reasons:

1. There is only energy in the water system because your city has pumps/water towers to give it pressure. So in a disaster, you running your hydro setup is just placing more strain on the water infra who are likely running on generators.

2. Hydro plants need huge amounts of water to provide power. To even power a single outlet, you are talking in the range of tens of thousands of gallons of water per hour. Your water bill would quickly eclipse the cost of just buying a generator.

---

Going back to natural gas, you are looking for an automatic transfer switch. When the power cuts, it disconnects you from the grid, turns on the generator automatically, and you then have power again. When the power is back, it switches you back to grid and turns generator off. Only downside is that there will be a several second power cut while generator turns on. You generally can only get this feature on midrange cost and up generators. For cost savings measures, you can also buy a manual transfer switch, with the obvious downside of you having to flip the switch and go start the genny.