The amount of filtered water and loose leaf tea that you use will depend on how much tea you'd like to make, and how big your container is. You'll need about 1.5-2 tsp of tea per 1 cup of water.
Add tea and water to your container, cover (don't push the plunger of the french press down yet), and refrigerate for about 12 hours.
Once the tea is done brewing, press down to strain or utilize whatever straining method you've decided to go with. If you're using a french press, go ahead and transfer the brewed tea to other containers if you aren't drinking it all right away. Much like coffee, if you leave cold brew tea in a french press it can get bitter.
Pour the tea into a cup with or without ice depending on your preference and sweeten as desired.