Why You Don't Drink Enough Water: What a National Survey Found
Updated: 1 day ago
Almost everyone agrees they should drink more water. Almost nobody does. The usual explanations are vague: busy day, forgot, don't like the taste. A survey published by the CDC lets us be more precise about who drinks too little and what goes with it.
The survey
In 2013 the CDC's journal Preventing Chronic Disease published an analysis of plain water intake among US adults using the 2007 Food Attitudes and Behaviors Survey, a national mail survey. The analysis covered 3,251 adults and asked how many cups of plain water they drank on a typical day, alongside questions about diet, exercise and demographics.
Here is how adults were distributed:
7 percent drank no plain water at all on a typical day
36 percent drank 1 to 3 cups
35 percent drank 4 to 7 cups
22 percent drank 8 or more cups
Two quick sums from that list. 78 percent of adults drank fewer than eight cups, the number most people have in their head as the goal. And 43 percent drank fewer than four cups, which is below the roughly four glasses of plain water a day that the average adult reported in NHANES 2009 to 2012.
What predicts drinking under four cups
The study reported adjusted odds ratios for drinking less than four cups a day. An odds ratio of 1.0 means no difference from the comparison group. 2.0 means the odds are doubled. Our method was simple: take every odds ratio the authors reported, drop the ones whose confidence interval crossed 1.0 (meaning no reliable effect), and rank the rest from strongest to weakest. This ranking does not appear in the paper.
Eating one cup or less of fruit and vegetables a day, versus 4.5 cups or more: odds ratio 3.0
No physical activity, versus 150 minutes or more a week: 1.7
Fast food more than once a week, versus none: 1.6
Fruit and vegetables between 1 and 4.5 cups a day, versus 4.5 or more: 1.6
Some physical activity but under 150 minutes a week: 1.5
Living in the Northeast, versus the South: 1.4
Age 55 or older, versus 18 to 34: 1.3
And the factors that did not matter:
Being female versus male: odds ratio 1.0, no difference
Age 35 to 54 versus 18 to 34: 0.9, not significant
Living in the Midwest or West versus the South: not significant
Fast food once a week versus none: not significant
Reading the ranking
The three strongest predictors of low water intake are all other daily habits: how many vegetables you eat, whether you exercise, and how often you eat fast food. The demographic factors are either weak (age, region) or absent (sex).
That tells you something about the mechanism. People are not failing to drink water because of who they are. They are failing because water drinking belongs to a cluster of small daily behaviors, and when the cluster slips, water slips with it. The person who skipped the salad and the walk is three times as likely to have skipped the water too.
It also means the fix is behavioral, not informational. The 78 percent who drink under eight cups do not lack a fact. They lack a prompt at the moment it matters.
Why older adults slip further
The one demographic that does show up is age. Adults 55 and over had 1.3 times the odds of drinking under four cups. A separate CDC analysis of NHANES 2009 to 2012 shows the same pattern with measured intake: men aged 60 and over averaged 2.92 liters of total water a day against 3.61 liters for men aged 20 to 39, a drop of 0.69 liters, about three 8-ounce glasses.
Thirst is a weaker signal with age, and the survey data suggests the habit weakens with it. If prompting matters for everyone, it matters most here.
The forgetting problem
Every one of the top predictors above is a habit that runs on cues. You eat vegetables when they are on the plate. You exercise when it is on the calendar. Water has no natural cue after the morning coffee; you drink when thirsty, and by then you have been behind for hours.
The practical answer is to give water a cue that does not depend on remembering. That is the whole design of Water Textapp. You set a goal in glasses, text a number each time you drink, and if you have not hit the goal by late morning or mid-afternoon it texts you. The check-in is the cue. The one-character reply is the log. There is nothing to open and nothing to remember.
A plan built on the data
Set a goal of eight glasses. Only 22 percent of adults reach it, so hitting it puts you in the top fifth.
Attach water to the habits that predict it. A glass with every serving of fruit or vegetables, and one before and after any exercise, lines up with the strongest associations in the survey.
Get a check-in you cannot ignore. The survey says low intake is a habit problem, and habit problems respond to prompts, not resolutions.
Count honestly for a week. The 43 percent under four cups mostly do not know they are in that group.
Try it by text
Water Textapp is the prompt. Text Hi to (646) 640-0771, reply with a daily goal like 8, and then text a number each time you drink. It keeps the total, tells you what is left, and checks in twice a day until you get there. It works on any phone that can text, with no app to install. Your first 20 messages are free, then one $9.99 a month subscription covers every Textapp. Details at textapp.co/apps/water.
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