Splash pads are fountains of fecal material; CDC reports 10K illnesses
arstechnica.com
arstechnica.com
UV seems straightforward, even as a retrofit — a UV sterilizer is not terribly expensive or large, and it can be installed downstream of the filter without any other complication. (UV works poorly in cloudy water, which is why it goes after the filter.)
Ozone is a mess. The concentrations of ozone that disinfect are also dangerous for people, so you need a “contact chamber” to let the ozone react, and you want to avoid spraying highly ozonated water at children.
It also seems like it might be useful to sterilize the filter every night — those filters can surely end up quite full of cryptosporidium oocysts that will live for a long time. I don’t know what one would sterilize it with, though. Maybe chlorine dioxide?
https://pubmed.ncbi.nlm.nih.gov/11990150/
In any case, IMO the volatility issue is a bit silly. Chlorine is indeed volatile, but chlorinated cyanurates are not, and one can, and should, have cyanuric acid mixed in with one’s chlorinated pool/splash pad water to “stabilize” the chlorine. (They do decrease the effecacy of the chlorine at any given concentration, but they make up for it by making it much easier to maintain an appropriate concentration.) And one can buy a (moderately expensive!) system to monitor and control, closed-loop, the chlorine concentration in the water, so maintaining an appropriate chlorine level in a public pool is not actually that hard.
The real problem here is that cryptosporidium is hard to kill.
And all of this assumes that you're just not concerned about cryptosporidium. The chlorine levels in a pool do not reliably kill cryptosporidium! So you need something like UV, which will kill it as it goes through the UV chamber.
A splash pad has huge load of junk and a small water volume. The one nice property is that almost all the exposure is to water that is fresh out of the pump and associated filters, which makes UV quite attractive.
The most reliable solution, of course, is to screen the people who are going to use your pool and don't allow anyone who has even a hint of crypto symptoms to get in.
I hope that most public pools invest in a UV system. It's hard to prevent some dumbass with diarrhea from deciding today was a good day to swim anyway. Lots of those types of people in the world.
https://www.teamlab.art/e/tokyo/
When you first enter the building, you put your belongings into lockers, including your socks and shoes. After some instructions, you walk up a slightly inclined ramp that has a wonderful heated river of water about ankle deep.
I realized this warm river of water was actually cleaning our feet! Shortly thereafter, you enter a room that has a very spongy/pillowy floor, thus drying your feet. To my surprise, the whole process almost gave me an icky feeling. :)
Their approach to floors and feet is one of my favourite things about Japan. No shoes in the house. No slippers on the tatami. Designated slippers for the toilet. Completely thought out and sane. Traditionally the Japanese life revolves around the floor - you eat sitting on the floor and you sleep on the floor. As such they built very strong processes around maintaining clean floors.
Shoes in the house is insane. Dogs (and humans) regularly excrete on the surfaces you walk on. Studies have found people who drive regularly traipse in lead around the house coming from petrol refilling.
I find the rest of the world's approach to feet and shoes completely upside down. An old roommate explained to me that only after you walk around your home barefoot do you appreciate how clean your floors are and more importantly how clean your feet are.
But it's worth pointing out this is over 25 years of data, or around 400 recorded cases/year.
I wouldn’t be surprised if it was well over 10k/year, but the CDC is conservative with their numbers for good reasons.
> with the largest sickening over 2,000 water frolickers in one go.
Lots of people experience isolated events of food-borne illnesses for a variety of reasons. But when a restaurant gets 2000 people sick in a short time frame, we shut it down...and correctly so!
The average annual rate is not terribly informative for making effective public health decisions because it smooths out most of the interesting bits.
For private health decisions (should my family go to a splash pad or not) the average rate, or chance of infection from one visit relative to other activities, would be more relevant.
Still gross though!
Imagine what we could have had in our communities if we hadn’t wasted $3,000,000,000,000 on Iraq.
A properly maintained (good luck!) DE filter might do the trick, but they’re messy enough that they’re banned in large parts of the country. Cartridge filters are usually rated at 10 microns, which is nowhere near good enough.
It would not be hard to make a significant improvement by just adding UV sterilization.
What we would've had was $3,000,000,000,000 less debt, and still no splash pad filtration.
The Iraq war was put on the credit card.
And boy is HN getting weird.
https://link.springer.com/article/10.1023/A:1010000230103?cj...
https://theonion.com/small-towns-cryptosporidium-daze-fails-...
Excited to see studies on how well different intervention strategies work.
I sympathize, though, with the maintainers of public pools. A nearly constant bather load comprised mostly of children emptying their bladders at will. It's probably a losing battle. And then periodically one of the little brats will poop in the water. God bless the maintenance guy who has to fish that out and then shock the pool into the safe zone again. Yuck.
I know the denominator is different - most children are exposed to potential flu vectors, while only some visit splash pads - but I think this article mostly sounds scary because poop is gross.
Chlorination isn't sufficient:
"maintaining germ-killing chlorine concentration is especially difficult for splash pads because the jets and sprays aerosolize chlorine, lowering the concentration.
Still, in most splash-pad linked outbreaks, standard chlorine concentrations aren't enough anyway."
Yeah, do that. Or do ozone and UV and filters and all the things. It is absolutely wild to me that this is in any way surprising to someone. It also did not need the weird descriptions of who has stuck poop where and how it ends up in the water - simply stating that kids inevitable poop in the water is kinda enough to understand the problem.
In any case I don't think there is any need to choose one over the other.
I never understood, both as a child and now, all the kids that swim in a pool with their mouth open, constantly ingesting and spitting out water. Can you not swim with your mouth closed? Do you have a nasal obstruction?