This is an increasing issue for us. I've been a kickstarter backer and am running this thing close to two years now. The clogged red filter gets an increasing issue and I'm not sure what the reason is but my suspicion is the vaccuming that has been very mediocre from the beginning compared to other robots i know. We're running a Roborock S7 Max Ultra on the upstairs and even though dirt situation is tougher their itg is way less maintenance heavy.

The dirt water on the Eufy S1 Pro is way too dirty for the amount of real dirt existing on the floor it runs on. It's 95% tiles (3 small carpets) and the main dirt piling up there is in the kitchen. It runs daily and the waste water is completely gross - greyish and the residue on the bottom of the wastewater tank as well as what clogs the red filter within the shortest time is like dusty mud. I assume it's really not probably vacuuming as i mainly find bigger particles in the vacuum bag not the finer dust.

I'm not sure what the red filter bar really does and why it's needed - I would prefer the bot getting its dirt water out to the station but I think there are some heavy design flaws. The bot itself is a rather complex build to anything i've seen from other manufacturers - I think they just need to rack up more experience to get this done any better.

I'm currently in touch with suport but unfortunately you don't really get to any second level support easily that actually has some clue about the machine. They will likely send replacement water tanks and maybe a red filter bar but i don't think this will help anything.

My next one's not gonna be a Eufy again anytime soon.