Tea and coffee could be restricted in schools to pupils over the age of 16 in plans to encourage a healthy diet.
Children are 'advised' to drink water and milk
It is an option being considered as part of a consultation exercise by the School Food Trust (SFT).
Teachers' unions say this is another example of official bodies meddling in areas where they should not interfere.
The SFT stresses it has no intention of issuing an outright ban on the traditional "British cuppa".
General secretary of the National Association of Head Teachers Mick Brookes said such advice would cut into people's civil liberties.
He said: "Words fail me.
"I can understand the anxiety about young people eating appropriate food. But this nannying really has to end."
The SFT, a government body, has drawn up a draft code of practice for drinks provided in schools and is now canvassing public opinion on its contents.
The code, which is voluntary, is a best practice guide and gives clear advice to schools on which drinks they should provide, based on current regulations relating to school food.
It recommends that pupils drink plain water, milk, fruit and vegetable juice and plain soya, rice or oat drinks.
The draft code states that "hot tea, coffee and low calorie hot chocolate are allowed although their nutritional value is minimal".
It continues: "They are included because the rules concerning food in schools affect the adults who teach and work in schools as well as some sixth forms, and as long as they are not consumed in excess, they have no adverse nutritional effects in either adults or older pupils.
"These drinks are unlikely to be offered to younger students because of the dangers of nutrient displacement of healthier drinks, the inappropriate addition of stimulants, and for safety reasons relating to the handling of hot beverages."
Parents and others with an interest in children's nutrition are being invited to take part in the public consultation exercise.
The SFT is emphasising that there will be no outright ban of tea and coffee in schools, but if the public wants to see further restrictions, they would "consider" including such recommendations in the code's final version.
An SFT spokeswoman said: "There has already been widespread buy-in from manufacturers to the spirit of the voluntary code and we are confident that the code will be widely supported by local authorities and schools.
"However, the 'British cuppa' is an institution and whilst we work hard to ensure young people have a varied and balanced diet we have never directly or indirectly suggested that the code should ban tea or coffee from schools - neither will be suggesting so."
The Association of School and College Leaders (ASCL) does not appreciate the SFT's actions.
ASCL general secretary Dr John Dunford said: "This is another example of the SFT trying to micro manage schools with the sort of decision that should be left to head teachers.
"I think heads are getting really fed up with being told how to manage the detail of school life."
Children's Minister Kevin Brennan said there would be no ban.
"Generations have grown up loving a cuppa - it's a staple of our national diet and nothing will change that."
The SFT plans to publish the final version of the code soon after the close of consultation (29 February), when all of the responses have been collated and summarised.
A supporting document will be published on the trust's website in spring 2008.
The code has been developed by a group of interested parties including drinks manufacturers, representatives of the drinks industry, food wholesalers and distributors, and others interested in promoting the nutritional welfare of children in school.
The SFT has pledged to review the code annually and update it as necessary.