“Make sure they stay hydrated” tells you nothing. Here are the actual numbers.

How much water per day The baseline is half an ounce per pound of body weight on regular days. A 70-pound kid needs about 35 oz of water. A 100-pound kid needs 50 oz.

On a game day, that number goes up. Add 16 oz for every 30-60 minutes of moderate activity. Hot weather or heavy sweating: add another 8 oz on top of that.

A 90-pound kid playing a 90-minute game in July heat needs roughly 60-70 oz across the day, not counting what they drank at meals.

Before the game 16 oz of water two hours before game time. Not a sports drink. Water.

Then 8 oz about 30 minutes before. Just a cup.

Most kids show up to games already behind on water because they didn’t drink anything in the morning. If your kid drank 4 oz of OJ at breakfast, they are starting the game dehydrated.

During the game 4-8 oz every 15-20 minutes. That’s a few good gulps at each water break, not a tiny sip.

Coaches control the water breaks, but you can reinforce the habit: your kid should drink every time they get a chance, not just when they feel thirsty. By the time they feel thirsty, they’re already 1-2% dehydrated. At 2% dehydration, reaction time and endurance drop measurably.

After the game 16-24 oz in the 30 minutes after the game ends. Then keep drinking through the rest of the day.

A simple check: look at the color of their urine about an hour after activity. Pale yellow means hydrated. Dark yellow or amber means drink more. Clear is actually fine but doesn’t mean they need to stop drinking.

The dehydration signs most parents miss Everyone knows dry mouth and thirst. But these show up late.

Earlier signs: headache during or after activity, feeling tired in the second half of a game when they should still have energy, muscle cramps that don’t have an obvious cause, irritability after a game, and trouble concentrating during competition.

A kid who gets a headache after every game probably isn’t drinking enough before and during. A kid who cramps in the second half of a 70-degree game probably came in under-hydrated.

The electrolyte question Electrolytes replace sodium, potassium, and magnesium lost in sweat. Sports drinks like Gatorade do this, but they also carry a significant sugar load.

For ages 5-10: water is enough for most activities. An electrolyte drink makes sense on very hot days (above 85 degrees) or during a long tournament. Not at every practice.

For ages 11-14: one 8-12 oz serving of a sports drink or an electrolyte mix per game session during hot or intense activity is reasonable. More than that and you’re adding sugar without proportional benefit.

Electrolyte packets like Nuun or Liquid IV mixed in water are a cleaner option than full-sugar sports drinks for most youth athletes. Lower sugar, same mineral replacement.

What doesn’t count as hydration Juice: high sugar, not a substitute for water. Fine at breakfast, not a hydration strategy.

Soda: no. Caffeine in soda is a diuretic at meaningful doses, which works against hydration. Also carbonation creates fullness before games.

Flavored milk: reasonable recovery drink after activity. Not a pre-game hydration choice.

Sports drinks before activity: the sugar spike before a game isn’t helpful and may cause a crash mid-game. Save them for during and after.

The simple version Water at every meal. Water two hours before the game. Water at every break during the game. Water after. If it’s hot and they’re sweating hard, add one electrolyte serving during or after. That covers 95% of youth athletes in 95% of situations.

The other 5% is when they’re playing three games in one day in July. That’s when the numbers above matter more.