Wash the skin of the limes for the lime juice. We're adding everything to the blender, so don't worry about peeling. Cut the limes into quarters and take out any seeds.
Put the limes, water and crushed ice into the blender. Blend for at least a couple of minutes. Taste the liquid and if it's too tart for you, add in sugar or sweetener to taste - up to 250g of sugar and equivalents of sweeteners.
Strain the lime juice mix to get a lovely coloured lime juice.
Optionally, use a soda charger, or a sodastream to give your lime juice a little fizz and turn it into limeade.