How do you drink more water?

People ask Google how to drink more water in dozens of ways: when you hate water, when you're not thirsty, when you keep forgetting. The questions are different. The answers mostly aren't.

How much water do you actually need?

Less precisely than the "8 glasses" rule suggests. The NHS says to aim for 6 to 8 cups or glasses of fluid a day, and calls that a guide.

The US National Academies put total water at about 3.7 litres a day for men and 2.7 for women, but that includes food, which supplies about a fifth of it. The European figures are 2.5 litres for men and 2.0 for women, food included too.

None of these are strict targets. Your size, the weather and how active you are all move the number.

Do tea and coffee count?

Yes. The NHS says water, lower-fat milk and lower-sugar drinks, including tea and coffee, all count. Harvard's Nutrition Source agrees that caffeinated drinks contribute to your daily water.

Food counts as well, especially fruit, vegetables and soup. What the NHS suggests limiting is fruit juice and smoothies: one small glass a day.

How can you tell you're drinking enough?

Look, don't count. The NHS advice is to drink enough that your pee is a pale yellow colour. Dark, strong-smelling pee and feeling thirsty are early signs you need more.

For most healthy people, the National Academies say thirst is a good guide. Two caveats from Harvard: some foods, medicines and vitamins change the colour, and thirst gets less reliable as you get older.

How do you drink more water when you keep forgetting?

Stop relying on remembering. Attach water to something that already happens every day.

Habit research recommends doing a new action in the same situation each time, ideally right after something in your existing routine. For water, that looks like:

• a full glass with every meal, which the CDC, Mayo Clinic and Harvard all suggest
• a refill every time you sit down at your desk
• a glass after you brush your teeth in the morning

The other half is keeping it in sight. A bottle on your desk gets drunk; one in your bag doesn't. Harvard's version is simple: fill a 20-ounce bottle four times a day and sip.

How do you drink more water when you hate water?

Change the water, not your willpower. The NHS suggests sparkling water, no-added-sugar squash, or a slice of lemon or lime. Harvard adds mint, cucumber, berries and orange zest.

Cold helps too. The CDC's tip is to freeze water in a bottle the night before, so it stays cold all day.

And remember that tea counts. If you'd rather have three cups of tea than three glasses of water, that's fine.

Do reminders and water tracker apps help?

For people who forget, it looks like they do, though the evidence is thin. In one trial with 85 people prone to kidney stones, 60% said not remembering was what kept them from drinking more. Those given a smart bottle with phone reminders increased their urine output by about 1.4 litres a day, against 0.8 litres with advice alone.

That's one trial, in people with a strong reason to drink. But the idea transfers: if forgetting is your problem, a reminder at the right moment fixes it. If disliking water is your problem, a tracker won't.

When do you need more?

The NHS lists four situations: when you're pregnant or breastfeeding, in a hot place, active for a long time, or ill or recovering. In a heatwave, it also suggests avoiding alcohol, caffeine and hot drinks.

Mayo Clinic adds the obvious one for exercise: drink before, during and after a workout.

Can you drink too much water?

Yes, but it's rare. Drinking a lot in a short time can make your sodium levels drop too low, a condition called hyponatremia, which can be life-threatening. Endurance athletes are most at risk, and Mayo's advice is to drink only as much as you sweat out.

If you have heart failure or kidney disease, your doctor may want you to drink less, not more. Ask before you set yourself a target.