It’s no secret that drinking enough water is good for us. Water helps regulate our body temperature, cushion our joints, transport nutrients to cells and clear the body of wastes, among its many other vital roles.
But knowing how much fluid you need each day – and the best sources to hydrate you – isn’t always straightforward. Perhaps that’s because there are many misconceptions about water and hydration.
Should you drink eight glasses of water each day or let thirst guide your intake? Is sparkling water as hydrating as plain water? Does coffee dehydrate you?
To help sort fact from fiction, here’s a guide to staying properly hydrated this summer.
What are signs you’re dehydrated?
Dehydration occurs when your body loses more fluid than you consume and doesn’t have enough to carry out its essential functions.
Every day, your body loses water through breathing, perspiration, urine and bowel movements.
When you sweat during exercise, you lose more water, particularly so if you exercise in hot and/or humid weather.
Warning signs of dehydration include light-headedness, fatigue, headache, loss of appetite, dry mouth, flushed skin and muscle cramps.
Even mild dehydration can impair cognitive and physical performance.
As dehydration progresses, extreme thirst, lack of sweating, heat intolerance, weakness, low blood pressure, rapid heartbeat and muscle spasms can occur.
Infants and young children, older adults and people who are physically active outdoors in warm weather are more susceptible to dehydration.
Can you rely on thirst to stay hydrated?
If your total body water falls by 1 to 2 per cent (mild dehydration), your body often lets you know by signalling thirst.
Research suggests that, under normal circumstances, most people can meet their hydration needs by drinking fluids with meals and when thirsty.
Trusting your thirst mechanism isn’t reliable for everyone, though. The body’s natural thirst perception diminishes in older adults and during vigorous exercise.
Check the colour of your urine to see if you’re drinking enough fluid. A pale, straw yellow colour indicates you’re hydrated. When dehydrated, urine becomes more concentrated and turns a dark yellow or amber colour.
Note that high-dose multivitamin and B vitamin supplements can turn your urine a bright neon-yellow colour.
Athletes should weigh themselves before and after exercise. Drink 500 ml of water for each pound of sweat loss.
How much water do you need each day?
The one-size-fits-all notion that we need to drink eight glasses of water a day is a myth.
Water requirements vary based on gender, age, diet, weather, activity level, individual sweat rates and medical history.
In general, the U.S.-based Institute of Medicine (now called the National Academy of Medicine) recommends healthy adults who live in temperate climates consume 2.2 (females) and 3.0 litres (males) of fluids each day to stay hydrated.
Children, ages one to three years, need one litre of water daily and four- to eight-year-olds require 1.2 litres.
Nine- to 13-year-olds need 1.6 litres (females) and 1.8 litres (males) daily.
Teenagers 14 to 18 years require more, 1.8 litres for females and 2.6 litres for males.
These intake guidelines don’t account for exercise or hot and humid weather, which drive up fluid requirements.
Daily fluid needs also increase during pregnancy (2.3 litres) and breastfeeding (3.1 litres).
Our diet, especially water-packed fruits and vegetables, provides additional fluids.
What counts as “water?”
Everything you drink – except for alcoholic beverages – counts toward your daily fluid requirements. (Alcohol is a diuretic, meaning it causes your body to lose water through urination.)
So, yes, caffeinated coffee and tea do contribute to your daily water intake.
Research suggests that the mild diuretic effect of caffeine diminishes with regular consumption. The water in coffee is also thought to negate any diuretic effects.
Carbonated water counts too. It hydrates your body just as well as plain water.
Should you consume electrolytes with your water?
Electrolytes are minerals that help maintain the body’s fluid balance and regulate muscle and nerve function. The main ones lost in sweat are sodium and chloride.
Consuming electrolytes with fluids during exercise has been shown to help delay fatigue, enhance physical performance and speed recovery in athletes.
Electrolytes are beneficial if you sweat a lot during intense exercise or you work out longer than one hour. Otherwise, plain water will do just fine.
Electrolytes are sold as powders and tablets and they’re a key ingredient in commercial sports drinks. Salty pickle juice (brine) is also trending for its electrolyte content.
Tips to increase daily water intake
To help hit your daily hydration goals, make a habit of drinking 500 ml of water with each meal.
If you don’t like plain water, flavour it with a slices of citrus fruit, pineapple chunks, cucumber slices or fresh mint leaves. Change it up with unsweetened flavoured sparkling water.
Keep a filled bottle or glass of water in plain sight on your desk or your kitchen counter.
To motivate you to drink at regular intervals throughout the day, consider buying a water bottle with time markings.
Leslie Beck, a Toronto-based private practice dietitian, is director of food and nutrition at Medcan. Follow her on Twitter @LeslieBeckRD
Leslie Beck