I use an old milk jug for this.
2 cups white vinegar
2 cups bicarb of soda
4 cups water
The bicarb and vinegar fizz, so combine slowly. I also add a FEW drops of essential oil. NO more than 20 b/c the stuff intensifies.
I add about half a cup to the final rinse and it works brilliantly. Better than just vinegar. Makes the clothes soft.
I also use bicarb to make Kim and Aggie's surface cleanser, which I pinched out of their book, but add essential oils to:
500ml water, 2 tablespoons lemon juice, 1/2 teaspoon of washing up liquid, 1 tablespoon bicarb and 1 teaspoon of borax. To this I add 1 drop tea tree, 2 drops lavender, 3 drops lemon and 3 drops orange oils. Pour into spray bottle and give it a shake before spraying.