Wow! Some of this brings back memories for me. I was born early 70s, I don't remember being thirsty (apart from one occasion) but as a child I'd have cereal with milk and a cup of tea for breakfast. At school there were no fountains and no one brought drinks with them.
At lunch time there would be pre poured plastic cups of water on the table, and I remember this distinctly, (this is the one occasion I remember being thirsty). There would be 4 boys on one side of the lunch table and 4 girls on the opposite side. I had been up to the serving hatch to get my free school meal and put my plastic plate down on the table and gulped my water. It wasn't until I got to the bottom of the cup that I realised someone had poured salt in it.
Salt cellars were the norm on the school dining room tables then. I was sick all over my lunch.
At dinner time we would have our evening meal, it was like it or do without, and the teapot would be stewing in the middle of the table. No cup of tea until we had cleared our plates.
There was no squash / diluted juice but I imagine if I wanted a drink of water it would have been fine. But when you're brought up on only having 3 drinks a day you adjust to that.
I don't drink tea now and haven't since my teens, can't stand the smell or taste of it. But I drink water like it's going out of fashion.
Some other things that have been mentioned. The smoking. My parents both smoked and had done since a young age. But it was encouraged in their youth and promoted as a good thing.
Sun exposure: sun screen didn't exist when I was a child. Many a Summer I had sunburnt skin and had to bathe in vinegar 'to draw the burn out'. Only on a Sunday though, we had a bath once a week and then it was bath soup. My mum would go in first, then my dad, then all the kids together. The same water getting murkier.
Leaving your kids home alone or outside of shops or pubs was the norm where I grew up. I babysat my cousin from the age of 10. I'd ride my bike to my auntie's on a Sunday afternoon, my auntie would go out to the pub and I'd be in charge of looking after my 2 cousins and stay over night. I'd cycle home on Monday morning, have my breakfast and get changed for school.
My parents used to go out to the pub every Saturday and Sunday night, smoked Regal and claimed free school meals and clothing grants.
The 70s and 80s were very different in terms of how children were treat, and a lot has changed because of the Children's Act in 1989 when the rights of children started to be implemented.