H2S is Hydrogen Sulfide. Some areas have H2S naturally in the water. It gives off a rotten egg smell. Mixing the water with air will get rid of most of the smell. So there are areas, apparently like in Texas Wellmans part of the country, where the old style air over water tanks are the only way to go. A bladder tank doesn’t let air mix with the water, and won’t get rid of the rotten egg smell. If I had H2S, I would also use a standard air over water tank system, and the larger the tank, the larger the air to water ratio.
However, most of the country does not have H2S. Where H2S is not present, I would only use a bladder tank. Back before bladder tanks existed, the everyday problems with standard air over water tanks were common knowledge. A bleeder orifice, check valve, Schrader valve, and air volume control are needed to maintain the air to water ration in a standard bladderless tank. These little parts are notorious for causing problems. The little hole in the bleeder will clog up. The above ground check valve wears out, which keeps the bleeder from opening up. The Schrader valve has to be in a fairly clean well house. Because the Schrader is where the air gets into the system, and I have seen them sucking in chicken feathers and such which isn’t good. The Schrader valve can plug up or start spurting water. If it spurts water, usually somebody will just screw a cap on the Schrader valve, which renders it inoperable. Then the Air Volume Control or AVC in the side of the tank, which lets out excess air, is always clogging up, spurting water, or the float in the tank just falls off. Regular maintenance is needed to maintain these parts and to make sure you have enough air in the tank.
The bladder tank was invented to eliminate these problems. The bladder separates the water from the air, so the air never needs recharging. This eliminates the four little moving parts that always caused problems with the old style tanks. The bladder tank basically requires no maintenance. And as Justin so eloquently put it a while back, people just won’t maintain a water system. They want to turn on a faucet when they want water, and turn off a faucet when they don’t, and nothing else. If you leave one thing for the homeowner to check or maintain, it won’t get done, the system will fail, and the pump man is responsible, because he didn’t install a maintenance free system. So I would never install a bladderless tank unless I had to deal with H2S or something similar.
A few “tens of gallons” stored in a tank would be nice for the first flush or two, but won’t last long when the power is off for three days. I would keep a generator handy, and run it once a day while everyone showers. Then I would fill some jugs for drinking water and fill a bathtub before shutting off the generator. A bathtub will hold more usable water than the largest pressure tank available. You can dip flushing and washing water from the tub for a long time.