Tabletop RO systems?

[MateoinLosAngeles]

I live in a rental with metal pipes and didn't feel comfortable messing too much with them to install an RO system. When considering options I realized that I could snuggly fit a tabletop RO system between the toilet and the bathtub, by installing a diverter in the toilet's cold water supply I could activate the RO system that way and simply fill up my jugs when needed and let the waste water go in the bathtub.

My other options would be to use the Washer machine's cold water supply, also using a diverter to send the water to either the RO System or the washer. This is located in the bathroom and the waste water could be flushed into the bathtub as well.

However, I'm not sure if a tabletop RO system would suffice living in Los Angeles, with a chlorinated water supply and pretty hard water. A tabletop system such as this Amazon.com has five stages. My guess is that the filters are smaller than the under the sink RO systems we're used to see (like this one Amazon.com) so they would need more frequent replacing.

But other than that, would a countertop RO system get the job done?