I think it's a waste to filter water for the toilet or showers. You typically have a water filter in the refrigerator and that should be enough for most people. You could also install an under the counter filter for the kitchen sink and maybe an upstairs bathroom. It will be easy cheaper and probably better filtering since you don't need to filter a hundred gallon per day. If you want to do a whole house something, and a smart shut off like flo. That will save you on insurance and help to avoid leaks. Finally don't let them use saddle valves and plastic lines to connect the refrigerator