We spend so much of our time worrying about measurements and feedings for babies, it's easy to forget once a child can move around and begin to decide what he wants for himself, that we should be still looking at what he's drinking.
Unless your child has a known allergy to it, milk is a great drink for small children. The nutrients in whole milk are a valuable way to get goodness down your child when he's rushing here and there, and still settling into a good eating routine. Aim to give your child about half a litre a day, possibly as one drink at night and one in the morning, unless some of that is taken with a breakfast cereal.
After he is two, you can give him semi-skimmed milk if you'd prefer, but between one and two, you should give him whole milk. (Before he is one you should only offer breast or formula milk as he cannot break down the content of cow's milk.)
Although a bottle is not recommended beyond the first birthday, some parents don't mind offering a bottle at bedtime as part of the winding-down routine. The reason why a cup is suggested is because children who 'nurse' a bottle for long periods can develop dental and speech problems. However, if your child likes to sit and drink a bottle down without carrying it around as a pacifier, you are probably fine.
Water may not seem as exciting as juice, but it's the core ingredient that your child's body needs. Try to give water between meals and limit juice. This will better quench your child's thirst and promote the habit of drinking water, which everyone should do.
These days you are unlikely to have 'dangerous' tap water in your home so tap is fine. If you give mineral water, make sure it is one that does not contain too many naturally occuring heavy minerals. Evian is a good one.
Do not overdo it. Having too much water can be dangerous too. Try keeping within the half to three-quarters of a litre a day maximum for a child (given that milk and some juice might take the max up to about a litre or so).
It is easy to think that juice is the healthiest thing for your child to drink. Certainly, pure juice NOT made from concentrate (and not 'juice drink') is nutritious, but also it contains natural sugars and it is quite acidic.
Try not to offer juice until your child is at least one-and-a-half so he gets into water as a preferred drink. He will love juice, but you should dilute it with three-parts water until he is about two or three, and then 50-50 with water until he is about five. This helps reduce the teeth's exposure to sugars and also dilutes the urine that otherwise can make wet nappies burn the skin.
Apple juice is popular but, though apples are full of goodness, the benefits are much depleted in juice form and other fruit juices are preferable.
Try to limit juices to mealtimes when food is also eaten and offer water at other times.