Stomach growling is caused by air moving around inside your bowels. It may be caused by two things:
- Your diet
- you may be swallowing air
The first point is usually caused by carbonated drinks (beer, soda) or too much fiber or fat in your diet. Some medicines (like antibiotics) can also cause air buildup in your bowels, and thus growling.
You may also have some intolerance that causes air buildup. (it may be a symptom of lactose or gluten intolerance).
Some hard candies, chewing gum, smoking and using drinking straws can also be a cause for growling.
The second point depends on your habits;
You may be swallowing a lot of air when swallowing saliva or food.
If you are a quick eater, try to slow down and take time to chew your food properly.
The above should also help with growls when you're hungry. If it diesn't i'd advise bringing a small snack with you to work, say, some fruit or a muesli bar, to enjoy when the growls get too much. It tends to help better and for longer, than just drinking water.
Instead of water, you should also try non-carbonated drinks that have a bit of "substance" or taste, eg. orange juice with pulp or a warm cup of tea.
Most medicinal approaches (eg. simeticon-based products) are for temporary use only, so i'd rather not suggest this unless you know whether the root of the growling lies in your diet or habits.