Anti-freeze ratio

We camp in freezing weather and do not put antifreeze in the fresh water tank. We have 50-gallon black and grey tanks and dump a gallon to three in each depending on how long we will be camping. We carry drinking water. We put a 5-gallon Igloo water cooler in the shower and use it for the toilet. We switch to paper plate and bowls and pre-cook most of our food then just microwave it. Most of the time our water will still flow through the lines but does freeze below 20 every time and I have insulated every line. If you're going to do this for an extended time I would recommend tank heaters which I am going to add this year. Hope this helps.

Sorry for confusion guys! We would like to continue to be able to use the fresh water and drainage systems when the temps are freezing at night and OK during the day. We NEVER drink the water from the tanks and the water would only be used for dishes, showers and toilet. So, how much antifreeze do I need to add to 35 gallons (the non-toxic RV type) to achieve this?

After thinking more on this, my guess is that the question is about the waste tank and the RV is expected to be heated. Please clarify.

chast wrote:
Would like to continue to use the fresh water system and want to add RV antifreeze to the tank.

I must be missing something :? ... you're not going to ingest any fresh water with antifreeze in it so why would you want to do this? :h

You don't add anti-freeze to the fresh water tank, you empty it and the water heater. The rest of the system should have 100 per cent anti-freeze.