Are there any extremely robust, leak-resistant on-faucet water purifiers?

As many of you may know, I love my Maytag portable dishwasher. However, I’m tired of filtering out the rust in my tap water with a Brita filter.

I’ve tried two Pur water filters connected like faucet => filter => dishwasher, but when I connect the dishwasher to the end of the filter (using the pass-through, so the water isn’t going through the filter), the pressure of the water overwhelms the cheap plastic (valves?) and water starts leaking out through the plastic housing.

There must be a better solution!