My first reaction was that If you want to drink or brush your teeth with boat water, I would rethink that idea.
General washing can be OK but if your boat sits for a while in the sun or hotter climates, the water will develop organic gunk . Adding a small amount of bleach to the water tank can slow down growth, but you still wouldn't want to drink it.
To a large extent, your fresh water quality depends on how warm your boating environment gets and how frequently your water tank is emptied, flushed and refilled.
The Seagull products state that they filter out a lot of contaminants but they are expensive to buy and fairly expensive to maintain. In addition they require supply water pressure they may be greater than your water system normally produces ( 25 to 100 psi or so). In addition, I would also recommend frequent flushing and refilling of the water tank to prolong filter life. I don't know if you have hot water in addition to cold but if you do, I am not sure how you woud address the requirement to also filter hot water
You can buy a lot of bottled water for the cost of the system but I suppose that isn't practical for long duration cruising.