Place the water into a large non reactive jar (glass or ceramic) and stir in the sugar.
Add the apple, you don't necessarily need it all. You can even use scraps left over from making an apple pie.
Cover with nut milk bag, a piece of cheesecloth or linen tea towel. Leave on your kitchen bench (no refrigeration) as directed.
Stir vigorously once or twice a day for 1 week if using sugar, 2 weeks if using honey.
The liquid will become very frothy as fermentation begins, especially after stirring.
When the colour of the liquid begins to deepen, taste it for the acidity. It should taste slightly acidic.
Strain out all the solids and return to the jar or bowl. Keep at room temperature for up to 1 month, until it is vinegary.
The healthy bacteria that create vinegar require oxygen for the process, so it is important not to seal the container with a lid until the vinegar is as strong as you want it to be.
Transfer into a glass bottle and keep in a dark pantry or cupboard until use.
To make raspberry vinegar, add as many raspberries to a sterilised jar or bottle as you would like, with the honey. Fill to 1cm of the top of the lid with apple scrap vinegar. Seal and keep in the fridge. Use for salads or as a drinking vinegar.