Is Poland’s tap water really protected by clams?

Over the years I've been making videos, a lot of people have got in touchto tell me that in Warsaw, in Poland, the tap water quality is testedand controlled by clams. They said that the city constantly runs a sample of its tap waterpast some mollusks. And those are filter feeders,so if there's a contaminant in the water, they will instinctively close. Sensors attached to themwill detect that and raise the alarm. And I didn't believe it.

It seemed too weird to me. And all the articles that I could findabout it seemed dodgy, somehow. They just set off red flagsin the research parts of my brain. There is a very arty Polish documentaryabout the system, and a lot of sites repost that film’s claimswithout even mentioning the source, just as a “look at thisfunny thing off in Poland!”. It felt like it could be a misinterpretedor mistranslated joke, or even a deliberate hoax by a filmmakerthat got out of control, and that the English speaking world.

Was just believing itbecause it was quirky and harmless enough. There have been plenty of fakethings like that spread about in the past, accidentally or otherwise. Or maybe the clam-sensors did exist,but it was a brief experiment that never went anywhere. Well, I'm now here in Warsaw,on a famous building in the middle of the river, with a Polishspeaking team showing me around. There is a lot of stuff we are not allowedto film here for security reasons. Inside here is critical infrastructure.

Plus, it is far too noisy down therefor me to talk, but I'm happy to report that yes,the clams are real. They actually do protect Warsaw, but the story's a little morecomplicated than that. IN POLISH: The important thing is: those clams aren'tthe only protection. They're not even the main part. This is still a modernwater treatment system, with 21st century sensors anddetectors to keep everyone safe.

This is part of a defense in depth,one part of an early warning system, one more alarm that can go off, like an airport that usesexplosive sniffing dogs… but also electronic detectors. The technical termfor this is “biomonitoring”, and it turns out from more research thatthis isn't the only place that does it. There are other water companies in Polandthat have similar setups, plus one in Minnesota, USA,and probably more that I haven't found. At which point I think I can say that:yes, the red flag in my head was wrong.

The clams in this buildingreally do help protect Warsaw.