Perfect, thanks much!
Aside from my little home project, I’m kind of curious if there is any kind of answer to my original question, even if it isn’t useful enough that anyone would bother to measure it.
Thought experiment: Let’s say I bought 5 of these dining sets so I had 10 benches to experiment on. I put them in some room or warehouse with 10% increment loads on all 10. The marketing declares the actual max to be 350 pounds, but who knows what it really is. So let’s say 50 pound increments to 500 pounds max.
I then leave these 10 benches in the warehouse for decades, with little sensors to track when each one fails. (Maybe defined as the center sags to an inch, maybe something has to hit the ground. Maybe track both events.)
Would it be reasonable to expect these 10 benches under varying loads to “fail” (however we define it) in the order of most weight first? If not, as in, no, that’s not a reasonable assumption, then fair enough, that fully answers my question. But if we do expect them to fail in (maybe even just approximate) order of most burdened first, and we graph those failure rates, then would there be a mathematical formula to predict how long to expect it to last given a specific load?
The simplest testing method would be increasing the weight on just one bench up to the failure point, and then repeating that test a particular number of times. The number of times you test it would be used to apply a safety factor. For instance if you test it maybe 4 or 5 times, and get repeatable results, depending on the use you might divide the safe load by 4 or more. That huge factor is because you have minimal results. Test it enough times and you might apply a safety factor of 2, but probably not less. For better results you would need to perform failure testing and analysis on each part of the bench individually, plus the joints where the bench seat attaches to the legs. You could then calculate the load capacity exactly, though still leaving safety factors because you can’t guarantee uniformity in something with that type of construction.
Real engineering studies may not have been performed on those benches. They may have successfully loaded them with 350 lbs. or whatever a few times and gone with it.
Surprised I’m the first to mention it, but is there some reason you don’t replace the 4 gpf toilet(s) with modern one(s) that would use about a third of the water? That much less work in those emergencies, and perhaps more importantly, you’ll save a ton of water and money every day of the year.
Early low-flow toilets had justifiably bad reputations, but the ones made in the last decade or two work fine. This one is advertised as being able to flush a bucketful of golf balls. I’ve bought and installed at least five of them in two houses. Obviously, I highly recommend it.
Low flow toilets are shit. Even if I take your word that they’re better than the garbage fire they used to be, I do not for a second believe they are as good as our “classic” toilets.
Reading up on wiki, it appears that the main design flaw in those early models was that they worked just like old gravity toilets, and since there is so much less water getting pulled by gravity, you’d have much less success per flush. So the newer models pressurize the water to make the smaller flushes more effective.
How does that work in my situation? Power’s been out for days, and I’m manually adding water to flush multiple toilets full of diarrhea. (We all got hit with bad takeout Friday night, power didn’t come back until Sunday. I bought a lot of water that Saturday. It was super gross.)
Does the pressurized toilet flush without power? Remember, no power means no water, which also means no water pressure. How do I manually refill a pressurized toilet tank with a jug of water? Is this an example of where you’d have to fill the bowl directly instead of the sealed bag in the tank?
Anything that results in me having to stir up diarrhea by pouring water directly into the bowl is a hard pass. (And I remain stunned that anyone would ever think that was a good idea in any way. And two different people have advocated for that insanity in this very thread. Please tell me you aren’t a third person suggesting I pour water directly in the bowl. The very idea is fucking disgusting.)
The toilet I linked to is not pressurized, and works just fine on much heavier loads than mere diarrhea. I’ve never owned a pressurized toilet, but AFAIK, most don’t require electricity.
I don’t know what the basis of your distrust of modern low-flow toilets is, but IME it is outdated. If others here confirm my experience, we might change your mind. But since I’m not the one hauling around four gallons of water or paying your water bills, I won’t try to disabuse you of your prejudice.
A @commasense says. Modern low-flows work great. They don’t need either water pressure or electricity. The big innovation is simply the opening at teh bottom of teh tank is bigger and so the much smaller flow happens faster enough to get everything moving.
The original low-flow models sucked becuase the manufactuerers tried to cheap it out just by using less water without changing the tooling to make stools, tanks, and drain hardware sized to the new task.
That shitty penny-pinching thinking was eventually squeezed out by smarter competitors who redesigned their products to go with the flow.
Early Low Flow toilets were often poorly engineered. They have gotten much better over the decades.
If you do decide to change to a low flow, check for reviews on it first.
Kohler & American Standard have many at the top of the Consumer Report’s review.
American Standard Champion (at Lowes) rates very well and no extras required. Even comes with a seat.
Well that’s encouraging. So the modern ones have tanks like old gravity toilets, so I can fill the clean/empty tanks like always? But only like 1/3 of the water my gravity toilets use? That’s worth considering.
If that’s the case, and I could get them all* upgraded for a couple/few grand total, then maybe the next time we lose power for a week I could do that instead of a full house generator as a (much) cheaper alternative. To be honest, none of us love the idea of storing combustible fuel longterm for a generator. Switching to low-flow toilets instead would triple my emergency water flush capacity, from 9 to 27. That’s, like, way plenty.
*Technically I have 3 toilets, but we only ever use two of them. Except during an extended power outage, of course.
If I had a water bill I wouldn’t need to manually refill my toilets. I’m on a well; it’s my water. I only pay electricity to run the well to pump it.
…or maybe just upgrade the one we never use, just in case it ends up not being great. But a “good enough” flush for 1/3rd the water could be clutch in an extended power outage situation.
I’m gratified that you are open to reconsidering your position on modern toilets. (I could say I’m miffed that you didn’t just take my word on it, but having someone as technically savvy as LSLGuy on my side was an obvious boost. 
Thanks to What_Exit, too.)
Much less than that, unless you have some unusual circumstances.The toilet I linked to is currently $200 at Lowes, and I think I’ve seen it on sale for as little as $150. And there are other decent toilets for well under $200.
I’ve replaced several toilets myself, and it’s really not a difficult DIY job as long as your current plumbing and the flange in the floor, that you attach the toilet to, are in decent shape. Even if you decide not to DIY, a plumber shouldn’t charge more than a couple hundred to do all of them in one call. Add the cost of the toilets, the total is around $1,000.
Or, if you you can do the installation yourself and want to be cautious, buy one, install it in the prime location, and if you don’t like it, move it to the secondary or tertiary site, try a different model, rinse and repeat. If you want to be cautious and not DIY, watch your plumber carefully during the first install, and do the later ones yourself with the benefit of that observation.
And of course, you can always reinstall the old wasteful one(s) if you really want to.
(I wonder if hardware stores permit returns on toilets? I would have tried to find out the one time I accidentally bought a round bowl instead of elongated, but I decided to move it to the guest bath that I never use.)