The science of hydration
Water is only half the story.
Drinking more water is good advice right up to the point it stops working. Hydration is a chemistry problem: fluid needs minerals to get where it is going. Here is how electrolytes actually work, and how much you need in a normal British week.
Signs and symptoms
Most people notice dehydration as something else entirely.
Thirst is a late signal, not an early one. By the time you feel it, your body has usually been running a small fluid deficit for a while. What you tend to notice first is a flat afternoon, a tight calf, or a headache you blame on the screen.
The mechanism
Why plain water can leave you thirsty.
Sweat is not just water. It carries sodium out with it, plus smaller amounts of potassium, magnesium and calcium. Replace the fluid without the salts and you dilute what is left, which nudges your body to hold less and pass more. That is the loop behind drinking two litres and still feeling parched.
Put the minerals back at the same time and the water has a reason to stay. Sodium drives the gradient that pulls fluid across the gut wall and into the bloodstream. Potassium moves it into the cells. Magnesium and calcium keep muscle and nerve signalling steady while it happens.
You sweat. Fluid and sodium leave together, at a rate that climbs fast in heat or hard effort.
You drink plain water. Volume comes back, mineral concentration drops further.
Your body corrects by shedding fluid. You are drinking, but not retaining.
Key nutrients
Four essential electrolytes, and the job each one does.
Spruce Daily Electrolytes are formulated with all four, designed by nutritionists for daily use rather than race-day carb loading. Below is what is in the sachet and why.
Sodium creates the gradient that pulls water in.
Sodium is the electrolyte you lose fastest through sweat. It sets up the osmotic gradient that moves water out of the gut and into the bloodstream, then helps you hold onto it rather than passing it straight through.
- Symbol
- Na⁺
- Job
- Fluid absorption
- Spruce source
- Pink Himalayan Salt
- Lost through
- Sweat, heat, alcohol
Potassium balances the water inside your cells.
Potassium works hand in hand with sodium to regulate fluid levels, support muscle contraction and help prevent the cramping that comes with dehydration. Sodium gets water in. Potassium decides where it goes.
- Symbol
- K⁺
- Job
- Cellular balance
- Spruce source
- Potassium Carbonate
- Lost through
- Sweat, illness
Magnesium keeps muscles and nerves from misfiring.
Magnesium is involved in hundreds of processes across the body, from muscle relaxation to normal nervous system function. It is also the mineral most people quietly run short on, which is why we give it a product of its own.
- Symbol
- Mg²⁺
- Job
- Muscle and nerve function
- Spruce source
- Magnesium Citrate
- Also in
- Peach Perfect Magnesium
Calcium is the one everyone forgets.
Best known for strong bones, calcium also plays a vital role in muscle function and nerve signalling, which makes it a key player in any complete hydration formula. Plenty of electrolyte drinks skip it. Ours does not.
- Symbol
- Ca²⁺
- Job
- Muscle and nerve signalling
- Spruce source
- Calcium Citrate
- Found in
- Daily Electrolytes
When it matters
Four very British moments to replenish electrolytes.
You do not need an electrolyte sachet with every glass of water. You do need one when the losses are real.
Anything over an hour
Park run, five-a-side, a long ride, a heavy session. Sweat losses stack up quickly once you pass the hour mark. One sachet before, one after.
Heatwaves and cabin air
A packed Central line in July, a Mediterranean holiday, a long-haul flight. Dry air and high temperatures pull fluid out faster than you notice.
Sunday, roughly 9am
Alcohol is a diuretic, so you finish the night down on both fluid and salts. Electrolytes before coffee is the fastest route back to human.
The 3pm slump
Headache, low energy, dry mouth by mid-afternoon is often a hydration debt rather than a caffeine deficit. Worth testing for a week.
Practical guide
How much water, how often, and where a sachet fits.
UK guidance sits at roughly 6 to 8 glasses of fluid a day for most adults, which includes tea, coffee, milk and the water in your food. Sweat, heat and alcohol raise that number. Electrolytes are what you add when the losses go past the everyday.
A Spruce Water Enhancer sachet turns plain water into something you actually want to finish. Real fruit powder, vitamins, zero sugar.
Daily Electrolytes with all four minerals. Training, heat, illness or the morning after a big one.
Peach Perfect Magnesium, 250mg of magnesium per sachet, for sleep, recovery and mood.
FAQs
Hydration questions, answered plainly.
What are electrolytes?
Electrolytes are minerals that carry an electrical charge when dissolved in water. The four that matter most for hydration are sodium, potassium, magnesium and calcium. They control how fluid moves in and out of your cells, and they fire your muscles and nerves.
Do I need electrolytes every day in the UK?
Not necessarily. If you are not sweating heavily, a normal diet plus enough fluid covers most people. Reach for electrolytes on training days, in hot weather, when you are ill, or the morning after alcohol. For everyday drinking, a water enhancer is usually the better fit.
How much water should I drink a day?
UK guidance is around 6 to 8 glasses of fluid daily, including tea, coffee and the water in food. Training, heat and alcohol all push that higher. Pale straw-coloured urine is the simplest day-to-day check.
Are electrolytes better than a sports drink?
They do different jobs. A traditional sports drink is mostly sugar for mid-event carbs, with a modest mineral dose. A modern electrolyte sachet flips it: meaningful minerals, no added sugar. If you are not racing, the sachet is usually the smarter choice.
Can electrolytes help a hangover?
Alcohol is a diuretic, so you lose both fluid and salts overnight. Replacing them on waking is one of the quickest ways to feel better. It is not a cure, but it beats another coffee on an empty tank.
Is it safe to take electrolytes daily?
For most healthy adults, yes. If you have high blood pressure, a kidney condition, or you take medication affected by sodium or potassium intake, check with your GP or pharmacist first.
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