Water and Caffeine: Daily Needs, Pregnancy Limits and Simple Tips

How much water do you need daily, and how much caffeine is safe? Health Canada's limits for adults and pregnancy, caffeine in common drinks and hydration tips.

Water and caffeine are part of almost everyone's day. Knowing roughly how much fluid you need, and how much caffeine is in your usual drinks, makes it easier to stay well hydrated and within safe limits, whether or not you are pregnant.

Add up your daily drinks with our free water and caffeine calculator, then read on for the guidelines behind it.

How much water do you need?

Health Canada's reference values suggest adult women need about 2.7 litres of total water a day. This includes water from all drinks and from food, such as fruit, vegetables, soups and yogurt. Food usually provides around 20% of it, so in practice that is roughly 2.2 litres (about 9 cups) from beverages.

Needs are higher in some situations:

• Pregnancy: about 3.0 litres of total water a day
• Breastfeeding: about 3.8 litres of total water a day
• Hot weather or heat waves
• Exercise, especially long or sweaty sessions
• Illness with fever, vomiting or diarrhea

These are general reference values, not strict targets. Most healthy people can let thirst guide them, while drinking a bit more in heat, during activity and when pregnant or breastfeeding. Water, milk, unsweetened plant-based beverages, tea and coffee all count toward your fluids.

Signs you may need more fluids

• feeling thirsty
• dark yellow, strong-smelling urine, or urinating less often
• dry mouth, lips or eyes
• headache, tiredness or feeling light-headed

Pale yellow urine is usually a sign that you are drinking enough.

How much caffeine is safe?

Health Canada's recommended maximum daily caffeine intake is:

• Healthy adults: up to 400 mg a day
• If you are pregnant, planning a pregnancy or breastfeeding: up to 300 mg a day
• Children and teens: no more than 2.5 mg per kilogram of body weight a day

Some people are more sensitive to caffeine and feel jittery, anxious or have trouble sleeping at lower amounts. It is fine to have less than the limit, or none at all.

Caffeine in common drinks

Caffeine varies a lot by brand, brewing method and cup size. These approximate amounts are from Health Canada:

• brewed coffee, 237 ml (8 oz): about 135 mg
• black tea, 237 ml: about 30 to 50 mg
• green tea, 237 ml: about 30 mg or more, depending on strength
• cola, 355 ml can: about 36 to 46 mg
• energy drink, 250 ml: often around 80 mg. Canadian rules cap caffeine at 180 mg per serving.

Watch your cup size. A large coffee-shop coffee can be two or more times the size of a 237 ml cup, which can put you close to the pregnancy limit in a single drink. Caffeine is also found in chocolate, some soft drinks, iced teas, pre-workout products and some pain medications.

Simple tips

• Keep a reusable water bottle within reach and refill it through the day.
• Drink a glass of water with each meal and snack.
• Flavour water with citrus, cucumber, berries or mint instead of choosing sugary drinks.
• If you are cutting back on caffeine, do it gradually to avoid headaches, or switch to half-caf or decaf.
• Have your last caffeinated drink earlier in the day if sleep is a problem.
• If you are pregnant and have nausea, try small, frequent sips rather than large amounts at once.

When to get medical advice

Talk to your doctor, midwife or pharmacist if you have kidney, heart or liver disease and have been told to limit fluids, or if you take medicines that affect fluid balance, such as diuretics. Ask about caffeine if you have heart rhythm problems, anxiety or reflux.

Get medical care the same day if you are pregnant and cannot keep fluids down for more than a day, or if you have signs of significant dehydration, such as very little urine, dizziness when standing or a racing heart. Call 9-1-1 or go to the emergency department for confusion, fainting, a very fast heartbeat or chest pain after consuming caffeine or energy drinks, or severe dehydration in a baby or older adult. In BC, you can call 8-1-1 any time for nurse advice.