Unless you really slam open the lid on your toilet, you’re not going to create enough turbulence to lift any water out of the bowl. The problem lies in the actual flush. When the toilet is flushed it splashes. Some droplets are big, others are much smaller (and these are the ones that stay airborne longer). A closed toilet is going to keep most of those droplets inside the bowl, where the vacuum created by the flush process will pull the majority of them back down. Without the lid, the droplets can get far enough away from the bowl that they won’t be pulled back down.
Also, regarding the new versus the old toilets, the old ones probably weren’t quite as bad for germ spreading, since most of them didn’t have the flush jet at the bottom, but they still had some splash even if it wasn’t easily noticeable; they just dumped the water in from the rim until enough had gone through to theoretically evacuate the bowl. Those bottom jets in the new design toilets are probably a big cause of the splashing, since less water means more positive pressure is needed to move things along.
The problem with most old toilets was, even though there was enough water to theoretically flush the thing, it was used very inefficiently. The old toilets, as noted, relied on the weight of the water in the bowl to flush, and only filled from small outlets around the rim. If they did become clogged, they were much more likely to overflow if you didn’t get the tank lid off and the valve shut in time.
New toilets flush much more efficiently, but often don’t have enough total fluid to do the job right, and the u-bend dimensions are therefore much more critical, since it has to be big enough not to clog but small enough that the tiny water volume will still work. Usually designers get the second part right, and fail on the first.
The ideal design would use maybe two to two-point-five gallons to flush instead of the three or more of the old rim-only toilets, but would have the jet at the bottom of the bowl to get things moving past the u-bend.
I will have to disagree on this. We are not talking about visible droplets here. If you look back at the article we are talking about water droplets that can remain suspended in the air for 90 minutes we are talking about something microscopic. A microscopic water droplet could be lifted out of a toilet bowl by the vacuum created by lifting the lid of that toilet.
As for the turbulence caused by lifting a lid I suggest this experiment (this may gross you out).
Take a puff of a cigarette of cigar, holding the toilet lid barely open gently blow the smoke in to the toilet bowl filling it with smoke as much as possible. Next lift the lid as you usually would and observe the path of the smoke exiting the bowl (it may help the visibility of the smoke to let the smoke clear before opening the lid). I think you may be surprised by the result.
Tiny particles can be carried very far by small air currents.
“The ideal design would use maybe two to two-point-five gallons to flush instead of the three or more of the old rim-only toilets, but would have the jet at the bottom of the bowl to get things moving past the u-bend.”
I bought fill tube/flapper valve assemblies for a designer toilet, think French Country, that uses a taller, narrower tank. Installing these in my regular “Lo-Flush” tanks, allows me to add an extra gallon to gallon and a half of water. They flush great!
Aha! A toilet expert. Very interesting information in your comment. Are you a plumber, engineer, or just a smart guy?