Originally written by Kelly Dwyer, MNT, BCHN® and posted on EatWellGrow.com.

How much water we need to drink for our health is a subject of great debate.

You’ve likely been told to drink 64 oz., or 8 glasses a day. But does that really make sense, considering humans’ wide range of body sizes and activity levels?

Maybe you’ve heard to drink when you’re thirsty. Logical idea, but thirst receptors can get out of whack with chronic dehydration, and they can become less reliable as we age.

Plus, we don’t always listen to our body’s thirst signals — maybe we’re busy working and don’t think about drinking water, or we confuse our thirst for hunger.

Water math

To calculate your daily water needs,* divide your weight in pounds by 2. Then drink that amount in ounces, as a minimum. Someone who weighs 150 lbs. would start at 75 oz.

From there, water needs increase with hot or dry weather, exercise, stress, caffeine, alcohol, sauna, high altitude, air travel or anything else that causes you to lose fluids, like diarrhea or vomiting. (Note: Some people limit water due to a specific health condition. I can help you navigate this.)

Many people are surprised by how much better they feel once they start drinking more water regularly. More energy. Improved focus. Reduced joint and muscle pain. Better quality sleep. Weight loss. Fewer headaches. I hear these things regularly from my clients.

Remember, water is H2O and those hydrogen and oxygen molecules split up and pair with other molecules in the body to tackle many important jobs for your health!

When multiple factors are depleting our fluids, someone 150 lbs. may easily need to drink 150 oz. of water. And with that increased fluid intake, they are diluting their electrolytes.

Electrolytes, and why they matter

Electrolytes are minerals (including calcium, sodium, potassium and magnesium), which play many roles in the body, some of which are critical — regulating fluid balance, acid-base balance and various muscle and nerve functions.

If you go for a long bike ride on a hot day, you sweat, and you drink a lot of water to quench your thirst. But that water doesn’t replace lost electrolytes. And if your food intake has been light, you’re likely depleted further. You’ll need to replace lost electrolytes.

If you’ve been sick with a fever and vomiting around the clock, you’ll need to replace electrolytes.

And sometimes, we forget that we’re layering multiple dehydrating activities on top of each other. A common one in Colorado: skiing all day + hot tubbing + a few alcoholic drinks + high altitude. Things can go downhill quickly.

Signs of electrolyte imbalance include headaches, dizziness, nausea, lethargy, muscle spasms and others.

Usually, you can prevent dehydration by drinking plenty of fluids the day before strenuous or prolonged activity, and by taking plenty of water and electrolytes with you during dehydrating activities.

When possible, skip the Gatorade and other drinks made with high fructose corn syrup and artificial flavors & dyes. Make your own electrolyte drink, or go for a supplement that you can mix into water, such as LMNT, Trace Minerals or NUUN.

All that being said, most people don’t need to add electrolytes with a moderate-intensity 45-60 min. workout. In this case, drinking enough water and eating a nutritious meal — with plenty of fruits and veggies — will do the trick.

Tips for drinking more water

• Measure the bottle or glass you use, then figure out how many times you need to refill it

• Drink most of your water between meals

• Eat plenty of water-dense foods — fruits and vegetables

• If you forget to drink enough water, set an alarm or add a squeeze of lemon to boost the appeal (or use the Water Llama app)

• Drink purified water, when possible.

• Plain water is important, but herbal teas and sparkling water count toward your total

• Don’t want to pee so much? Well… here’s a little tough love. Peeing more is OK. It’s part of what our bodies are meant to do.

• If drinking more water wakes you up in the night, load up on your fluids earlier each day and taper off in the evening

*IMPORTANT NOTE: The information in this article does not constitute medical advice. Please talk to your doctor about your fluid needs and use of electrolyte supplements.