# Travel >> Transportation >> RV

How to Add Antifreeze to an RV's Black Water Tank in the Winter

If you're using your recreational vehicle's septic system during the winter months, you'll need to winterize it to keep its pipes from freezing. A must-do task is adding antifreeze to your RV's black water tank, where all the waste from your toilet is stored. Be certain to use the non-toxic kind of antifreeze designed for RV use, not for regular vehicles. Many RV owners also add antifreeze to their gray water holding tanks, and often don't use the sinks in the winter to prevent pipes from freezing.

RV antifreeze

Instructions

- 1
  Empty your black water tank. This allows you to get an accurate reading on the amount of black water and antifreeze you'll eventually have in the tank.
- 2
  Pour one liter of antifreeze down the toilet. A good rule of thumb is one-to-one; when you have one liter of antifreeze, it should be enough for about one liter of waste. Since your tank started empty, one liter is enough to start off with.
- 3
  Add another liter of antifreeze after you've deposited about the same amount of black water matter -- flushed materials from your toilet -- into the tank. Keep a tally of how much antifreeze you've added so you know when your mixture is getting too diluted.