In my youth, maybe a can or two a day. A 20-oz bottle if i was splurging, although I’d occansionally have a small binge.
Today, I’m somewhat ashamed to admit my workday consumption is usually north of 100oz.
In my youth, soda was a luxury good my parents got in returnable glass bottles and only drank for themselves, sparingly. My brother and I got store brand Kool-Aid. In my mid-teen years, generic soda was cheaper so we got that. At college, it was on tap. So, yeah, I drank a lot of soda between then and less than a year ago. Since then I’ve been trying to drink water or milk (and coffee) instead. Long story short, no answer fits.
If we’re counting plain soda water, it’s about the same (i.e., around 30-32 ounces per day). Aside from soda water, I drink diet 7-Up, Sprite, or Sierra Mist. My carbonated beverage of choice used to be Diet Coke but, as another poster said, acid reflux put an end to my consumption.
First of all, I love soda. In my teens and early twenties I probably averaged 3-4 cans a day. And we’re talking regular pop back then, never diet. Now it’s more like 1-2, and at least half of them are diet because that’s what my wife likes.
People say it’s one of the worst things for you, but I don’t care. I love it.
People say that, but the truth is, there are a lot of things worse and you’re gonna die of something, eventually.
I drank a fair amount of soda on a daily basis growing up.
Now, I almost never drink it, so I think that counts as considerably less.
More now - In the 60’s & 70’s (when I was growing up) pop, as we call it in NE Minnesota, was never in the house. It was only for special occasions. My mom would buy 24 Shasta or Gold Medal cans of pop when we spent our 2 weeks at the cabin in the summer. I don’t think I ever had a real Coke or Pepsi until I was a teenager. We drank kool-aid or milk at home. As a teenager, I probably had Tab once in awhile. But now I have at least one Diet Coke per day. One for sure at lunchtime (I need the caffeine or I get a headache!) and it depends on what I have for supper or evening snack. If it’s fast food or pizza, I’ll have a Diet Coke for sure. If I have a salty snack in the evening I would have a Diet Coke then too. Otherwise, I drink ice water.
There’s people in this thread that drink more beer a day than I do pop. I don’t know how they could imply their beverage is less harmful than mine.
Used to drink a lot. Gamer, so it was a habit.
Once I hit 30, the carbonation started to upset my stomach and digestion something fierce. By 40, it was a decision as to whether I wanted to deal with the after affects or not - but sometimes, your pizza just requires an icy coke. 
More now than as a teen/young adult, but less than in my 30s.
Soda was a rare treat when I was a kid. My mom didn’t buy it, and we rarely ate out. I really liked milk as a teenager.
In my 20s I drank mostly beer.
In my 30s I had stopped drinking beer and replaced it with Mountain Dew, which I drank in quantities similar to, and even in excess of the beer of my 20s. A lot of that was drinking Mountain Dew for the caffeine while I was at work. Working in a kitchen, trying to drink coffee is useless, because you pour a hot cup, and by the time you go for a second sip it’s gone cold, and their are few things worse than getting a mouthful of cold coffee when you were expecting hot.
From my 40s and now into my 50s, energy drinks have mostly replaced the Mountain Dew for work, and I don’t drink those in nearly the same quantity. At home, it’s mostly plain water and coffee (because I can actually enjoy the coffee while it’s still hot).
Way less. My wife and son went through a diet soda phase in the '90s, my own usage spiked then, but after a while the expense and just plain lousy taste (to say nothing of the non-nutritive aspect) got to me and I quit.
Now, just a few blood orange sodas around for mixers, that’s it.
My daughter is an interesting person wrt soda consumption.
She is 27 and has consumed less than 12 ounces of soda in those 27 years. She was breast fed exclusively as a baby (never so much as a single bottle), then weaned from breast to a sippy cup with water or milk. She drank nothing but milk or water for her next few years. When offered a sip of soda she found it revolting.
In a restaurant today she will order water. She will drink wine to be sociable, but if she tries even a sip of some soda it makes her cough.
You’re lucky. So many kids today drink a lot more soda than our generation.
My mom packed a can of soda in my lunch for school. That one can was all the soda I had for the day.
Mom would only buy a case of soda (24cans) each month. It had to last or there was no more soda until she bought more on the 1st.
Today people are buying 3 liter bottles of Soda. Constantly refilling their glass all day. It goes flat fast in those big bottles and that encourages people to drink it quicker. That’s just not healthy.
unfortunately I was pretty much born a soda drinker although grandma had us drink tea and kool aid … but once I moved to moms house when I was 12 it was over with
Soda was pretty much the only liquid mom consumed like 1-2 Shasta 3 liters a day… and we drank hers when she wasn’t looking but she got so bad that when she woke up she would down what ever glass had left over even if it was 2 days old before she opened her eyes … once otr twice a day she drank tea or water
when I was in hs/college my doctor specifically banned me from drinking jolt cola as I was 3 steps away from a heart attack because of the 5 or 6 I drank a day (the local college cafeteria banned me from buying it a picture of me drinking one was taped to the register …thanks to his niece who taught there ratted me out )
but for almost a year but decided the heck with it and just cut down to 0-3 a day now my doctor is of the mind " no one needs anything carbonated"
I used to drink several on an average day. Orange soda was one of my favorites as a teenager, then Dr. Pepper in my 20’s. Now I drink water most of the time. Sometimes when I go out to eat I will have sweet tea or a soda because I don’t like the taste of most city water.
Slightly more, in that I now drink it when I eat Chinese food. I never ate Chinese food as a kid.
I still drink a fair bit, but I used to be a 2L bottle of Diet Coke every day. Now I drink a lot more water with the “flavor enhancer” squeeze in flavorings. Still an artificial sugar product, but less acid and no fizz. Easier to bring into work too.
The only soda I was allowed to drink as a kid was Diet Cherry 7-Up, which was way too fizzy for me. Then in high school I started drinking Pepsi. My parents didn’t really approve the caffeine, but I was old enough to decide for myself. In college I’d work a night shift, walking to the 7Eleven 3 times a night to fill up a 52-oz mug. I gradually switched to Diet Pepsi or Diet Coke when my metabolism slowed; now I can’t handle any stickiness in a soda.
These days I always have a Diet Coke in arm’s reach, when I’m driving or working or eating. I’ll have a beer or wine when I get home, but usually follow it with another can of Diet Coke. Probably 100 oz a day.
Actually, I find that I’m dehydrated since I switched to water. I drink a couple of cups of coffee but then because water holds no excitement, I don’t get around to drinking it. Soda was fun so I drank a lot more of it. And more liquids is better than being dehydrated. (I know, caffeine is a diuretic so it probably negated some of the hydration benefits of the soda, but the net effect was probably better.)
I never drank fulk-sugar pop, it was too sweet for my taste, but in high school and college I would drink 3-4 cans of diet soda per day. I gave it up completely during my pregnancies and when I resumed drinking pop, I reduced it to a single can per day. That is still what I drink today - one can of Diet Dr. Pepper per day in the midafternoon.