Overflowing reverse osmosis water purifier?

November 2, 2023 8:31 AM

I've emailed the manufacturer, but I'm wondering if someone might be able to mechanically reason this through. I've had a relatively straightforward, countertop (manually tank-filled) reverse osmosis water purifier for over a year, and it's had no problems. I just replaced all the filters, and now, for some reason, it overflows the carafe instead of filling it to the top.

I don't think there's a "shut off trigger," because if the carafe wasn't completely empty before starting a fill cycle it would overflow, in the past. So I think it's somehow blindly calculating how much water has been purified and then shutting off. I'm not sure if it's just a timer.

In any case, post filter change, it's gone from filling exactly to the top (actually a couple centimeters from the top) to considerably overflowing.

I'm pretty sure I chose the correct filters, and I'm pretty sure I installed them correctly. And that's as far as I've gotten. They haven't "settled in"; the new behavior has persisted for a couple weeks.

Does anybody have any ideas for what to poke or prod or tweak to get back the old behavior?

posted by zeek321 to Home & Garden (2 answers total)

Is the reject water output still the same, or has it decreased? My first thought is that, if they are installed correctly, there is some flaw in one or more of the filters that is allowing more water to pass through without being properly filtered.
posted by velocipedestrienne at 12:33 PM on November 2, 2023

It could be lots of things I guess. Like vp says if the ro filter is damaged/faulty and letting water through that would increase the flow rate a lot more than it is expecting. The other filters don't really have very much effect on the flow rate.

It would be odd for a machine not to have some way of regulating the amount of water - RO machines without a drain usually put impurities back into the tank and cut off once the tank gets down to a certain level (that's why they always say to empty the tank completely when refilling) - maybe it's not detecting the tank low level switch properly or some sort of float switch is stuck.

Or if internally it is measuring the amount of water using a flow meter that spins, that could be stuck - most sane machines would cut off if they detect no flow but who knows.

It would help to know the model of the machine and if the filters were definitely from the machine manufacturer or if they could be cheaper versions (it's sometimes very hard to tell when buying online). If you still have the original RO filter you could try popping that back in to test and see if it goes back to the old behavior.
posted by samj at 12:37 AM on November 3, 2023