A point of use water filter would be fine, but you still have to "kill" the problem. We use a Brita filter the kind you pour the water in a pitcher.
But we have a fine mesh screen in front of the water pump (my CD 25 does not have one, and I am going to put one in next week). Also remember that there are some micro-organisms which are not killed with Chlorox/bleach. (Cysts, such as Giardia and a fine filter is necessary for that)
I agree with Pat, that the 1/4 cup a gallon is pretty concentrated. But, some folks recommend a cup per 10 gallons. A cup is 8 oz, so 1/4 cup would be 2 oz. Generally "sanitizing" bleach is one tablespoon a gallon. A table spoon is 0.5 oz.. For just "purification" 8 to 16 drops a gallon is the recommended amount. One ounce equals 360 drops... Also check the concentration of Bleach, be sure it is pure bleach, and Bleach looses about 50% of its concentration in a year's storage.
Is an excess of chlorox going to damage anything in the system? Chlorox is hard on seals and rubber components--and it may be a little hard on the pump. I also usually go with a 2 to 8 hours of contact time--which is plenty. I would not go with over 24 hours. Be sure and get the concentrated bleach solution into the water heater for the "hot" water side, and all of the cold water tubing (including shower and deck fresh water wash down). Keep the water system pressurized while the bleach is sitting in the llines.
Another old RV trick is that is there are any tanks which you think might be clinging, put some ice cubes into the tank, and drive around until they melt (with the chlorox)--the ice cubes are mildly abrasive, will not harm the tank and help to clean the walls of the tanks.
I agree with the baking soda. Never tried the Vodka. (For killing bacteria in laboratory conditions, red wine ranked 3 to 4 times more effective than pure alcohol or tequila. The effective ingredient is believed to be phenol compounds enhanced from charred wood of the wine-aging casks.) It is difficult to get the chlorox taste out of the tanks. We would sanitize our water tanks every 6 months when full time cruising--I still do this every 6 months, even with leaving tanks "empty" during the winter and frequent usage the rest of the year.
Depending on where we pick up the water, we like to filter the water going into the tank, then add our own bleach solution. There are some pretty nasty smelling and tasting waters, plus some which have particles in the water, which we like to filter out--if you use a charcole filter, be sure and add the chlorox.