Drinking water is important.  When and how much to drink is just as important and this is something we do not always think about.   Every cell in our body requires water to function properly including our digestive system, heart, lungs, and brain.   No matter how much you should be consuming, drinking water consistently throughout the day is important.  As well, there are specific times during the day when drinking water can really be beneficial.

When you wake up:

Before you reach for coffee, drink one or two cups of water. You wake up dehydrated so starting your day with some water can help get your dehydration topped up.  This can also be important if you take medication first thing in the morning.  Once you have had your water then feel free to reach for that coffee.  That coffee counts as fluids too!

Before a meal:

To help regulate hunger, have a glass of water before you eat.  This can help fill you up and help control the amount you eat.

After a meal:

Drinking water with food helps aid in digestion especially with high fibre foods.  As fibre moves through your system, it absorbs water to help keep things regular. Therefore, if you are eating a high plant based meal include water.

Mid afternoon:

Instead of reaching for a coffee to help pick you up out of a mid afternoon slump, drink a glass of water.  Dehydration can cause fatigue, anger, hostility, confusion, and depression so try drinking a glass of water to perk you up.

When you have a headache:

A headache can be a symptom of dehydration and can trigger migraines. Reach for a glass of water the next time a headache comes on.  If you are susceptible to migraines, try increasing your daily water intake.

Before, during, and after exercise:

Start getting hydrated a day or two before your workout.  Drinking a huge amount of water right before a workout will not reach your muscles or other tissues for quite a while.  Instead, it will slosh around in your stomach making you feel bloated.

Before bedtime:

Have a sip or two of water before going to bed.  Too much and you will have to get up often during the night to pee disturbing your sleep.  Keep a glass of water by your bedside so you can have a sip in case you wake up thirsty.

https://www.everydayhealth.com/healthy-living/8-best-times-drink-water/