I bought a 2nd-hand Brita water pitcher that looks like that in the pic.
It has a spinning plastic mechanism that mates with the cartridge. I have another Brita pitcher that is almost identical but it does not have the spinning mechanism. The pinning plastic bit block water when at rest. Water can only plass when a filter is inserted because a genuine “Brita”™ filter has a grooved cylinder that forces the plastic to spin ~45° and unblock the outlet.

The affordable generic Brita knock-off filters lack the grooved cylinder, so they are incompatible with one of my pitchers.

I’m not sure this is a crappy design. It seems to not be documented (according to my attempt at searching). Is there a sensible reason for having the spinning mechanism? It cannot be to fuck with the generic cartridge producers because it seems Brita abandoned that design themselves.

When I had one there was no spinny bit so can't help. But will say that a built-in system is much cheaper, zero faff and much less waste!

Not sure what you mean by built-in system. Is that like a whole house installation?

Never seen that, that’s super shitty! I’ve got three brands of filters including a brita, but none of them have weird ass water DRM. I will make sure to not purchase anything Brita if they’re doing things like this.

I'm not aware of whole house systems as you only generally take drinking water from the kitchen taps, so you can either fit a side tap like linked or one that feeds into the main sink tap. You only need to change the filter each 6-12 months. I've found it far less FAFF than a jug. It is a little slow compared to the main tap but it's an acceptable a trade off.

https://www.wickes.co.uk/BWT-Inline-Drinking-Water-Filter-Kit/p/149680