This one's for the jam makers out there. Instead of buying commercial pectin, make your own from fruit scraps.
Citrus peels and pips and apple and quince skins and cores have really high levels of pectin, which you need to make your jam set.
Pop scraps in a saucepan, cover with water and gently simmer for 20 minutes or so. Strain and store in a container or jar in the fridge or freezer.
Instead of adding water to your next batch of jam, add your pectin stock and watch it set before your eyes.