Roasted barley tea is the best drink for summer, called also
mugi-cha in japan (麦茶), it is a popular tisane made from roasted
barley. In Japan, it is regarded as a summer beverage. Many people in Japan believe that mugicha helps to cleanse the body.
You can buy prepared mugi-cha from shops, but I prefer to prepare it at home. I bought a bag of roasted barley (198yen, topvalue brand), the bag contains 52 small bags. I put one small bag in 1.5l of water and put it in the fridge for about 1 or 2 hours and the mugi-cha is ready.
You can give mugi-cha to children, it has no side effects. In the nursery school where my son is, they start to give mugi-cha from age 6 months. In shops specialized with baby food, it is possible to find mugi-cha for babies.