For the tastiest results, use tap water (filtered, if that's your preference), and fresh, unbruised produce for your infusions – if you're using skin-on fruit, especially citrus fruits, organic is a better choice. Thinly slice harder produce like pears, as this helps to release the flavour; meanwhile, soft fruits, such as berries or lemons, can be thickly cut or added whole. Tear herbs before adding them in, and keep delicate flowers in a tea strainer, or freeze them beforehand. You should leave your water to infuse for 1-2 hours, then keep it chilled in the fridge for a day at the most.