Get diagnosed with chronic or acute bronchitis, and both your doctor and your trusted online sources of health information will quickly tell you about the importance of proper hydration. To name to examples from opposite sides of "the pond", the US National Library of Medicine  and the British National Health Service  both advise people suffering from acute bronchitis to make sure they drink plenty of fluids — the latter elaborating that proper hydration makes coughing up all that phlegm easier.
First Off, Let's Take A Look At The Importance Of Proper Hydration In General
The fact that we need water to stay alive is apparent to all of us — fail to consume fluids (including those found in food and non-water drinks), and you won't last more than a couple of days. This is no surprise when you realize that 55 to 75 percent of a human's body weight is actually water.
Drinking water but not enough can, meanwhile, result in :
- Decreased physical performance
- Everything you do being harder
- Reduced ability to thermoregulate
- A decline in cognitive function, including short-term memory deficiencies, mood swings, and a lack of concentration
- When more than mild dehydration sets in, your kidney and heart functions are at risk, you may experience delirium, your blood pressure will fall, and any chronic diseases you have may get worse.
Chronic dehydration, much of it low-level, is more common than you might think — especially in the elderly population. One study suggested that 48 percent of older adults suffer from it . To make sure you're not suffering from chronic dehydration, make an effort to drink between 30 and 50 ounces, or one to 1.5 liters, of water every single day .
Suffering From Acute Or Chronic Bronchitis: What Do You Need To Know About Hydration?
Research into the effects of hydration focuses on those patients with chronic bronchitis. As we saw the NHS explain above, proper hydration is considered especially important in people with bronchitis because it is supposed to aid in the production and expulsion of the mucus clogging your lungs up.
Another study identified proper hydration as one of many factors that can help manage bronchitis better, along with a healthy diet, supplemental oxygen, strengthening the respiratory muscles, not smoking, and in some cases antibiotics. 
As far as acute bronchitis goes, one review concluded that "there is currently no evidence for or against the recommendation to increase fluids in acute respiratory infections" .
Where Does That Leave You?
The absence of clear evidence that people with chronic bronchitis, acute bronchitis, and other respiratory diseases benefit from increased fluid intake (that is, more than the normal recommended amount) in no way means that examining how much water you're really getting isn't in your interest. You still need to be properly hydrated — and you may not be.
What Else Do I Need To Know?
Most cases of acute bronchitis actually do pass on their own without medication or seeing a doctor — and antibiotics won't benefit you in most cases, since they only treat bacterial infections. Besides proper hydration, try to eat well, rest, and use a fever reducer and pain killer and perhaps a cough suppressant. You could also try steam inhalation therapy for bronchitis. If you are wheezing and really short of breath, it is definitely time to see a doctor for acute bronchitis! In severe cases, you may be prescribed a bronchodilator (inhaler). 
The same holds true for people with chronic bronchitis, with the addition that they'll have to adhere to their prescribed medication regime, which may include things like the Symbicort turbuhaler.