We are a family of 6 and would be lucky to drink 6 litres of milk a week. I actually don't like milk as a product as I think we drink way more as a country than we need to. I also feel a bit icky about the whole ethical treatment of dairy cows (slaughter of male calves, damage to the female cows from constantly producing milk etc). I gave up dairy once years ago and never felt better.
So I try and discourage my kids from drinking too much of it.