💧 How much water do you actually need?

Antonia here – one of TDA’s editors and, ironically, the least hydrated person in the office. It’s a pleasure to be in your inbox on this warm Sunday morning! With the weather heating up, it feels like the perfect time to talk all things hydration. So grab your favourite vessel, fill it to the brim, and let’s dive in.

It feels like everyone’s got an emotional support water bottle these days – the bigger, the better. We lug them to work, Pilates, and brunch… yet somehow still end the day wondering why our lips feel like the Simpson Desert.

The eight-glasses-a-day rule has been drilled into us for decades – but who actually decided that was the magic number? And is it true, or just another wellness myth that got wildly out of hand (looking at you, celery juice)?

Oh, more more thing before we get into it: today’s newsletter is sponsored by BRITA – makers of the snazzy water filter jugs. Saying that, this content has been made using our normal editorial processes.

It’s widely believed that the eight-cups-a-day rule dates back to 1945, when the US National Research Council suggested adults should consume about 2.5 litres of water a day. Sensible enough. But there’s one part that often gets lost. They also said: “Most of this quantity is contained in prepared foods.” 

Yep – your morning coffee, lunchtime soup, and post-dinner watermelon all count. Somewhere along the line, that nuance got lost, and “2.5 litres including food” turned into “eight full glasses of pure H₂O or you’re doing life wrong.”

Now, to be clear, that doesn’t mean we just throw out eight cups a day. It’s still the widely accepted, official guideline – including here in Australia, where the Federal Government recommends around eight to ten cups of fluids a day (depending on your gender and activity level).That’s another thing: Hydration isn’t one-size-fits-all – it’s surprisingly personal, even if the guideline gives you a solid benchmark.

Even though the guidelines are widely known, most of us still aren’t hitting those numbers. Research from BRITA found that four in five Australians aren’t drinking enough water each day. Not because we don’t know better, but because we… just forget (that was 41% of respondents) or claim we’re “too busy” (29%). 

Sound familiar? That afternoon brain fog, that mid-meeting struggle to focus, the crankiness that hits right before dinner… maybe it’s not just a caffeine crisis. Maybe it’s dehydration in disguise.

A key question to understand is: why does this actually matter? How am I affecting my overall wellbeing when I don’t meet that eighth cup?

But beyond the physical body, dehydration also has a huge impact on our minds. Even mild dehydration doesn’t just make you thirsty – it messes with your brain. Losing just 1–2% of your body’s water can slow down concentration, increase tiredness, and make it harder to regulate emotions (basically, your brain goes into low-power mode).

BRITA’s research backs that up: 82% of Australians say being dehydrated affects their performance – from focus and stress management to creativity and mood. So if you’ve ever felt foggy, flat, or snappy by 3pm, your brain might not need another coffee… it might just need water.

Instead of turning water into a chore (or competitive sport), behavioural scientist Dr Gina Cleo tells TDA that we should implement mindful hydration – making water part of our everyday rhythm rather than something you chase.

“Our brains thrive on routine,” she explains. “Linking water to existing habits – like a glass when you sit down to work, or another with lunch – makes it feel easy and natural.”

This closes the knowing–doing gap: you know you should hydrate, now you actually do it. Hydration isn’t about willpower; it’s about small, repeatable choices that stick.

Only 27% of Australians say they try to stay hydrated consistently, with most treating it as an occasional priority – during exercise, hot days, or when they’re already feeling sluggish. The trick isn’t chasing a magic number, it’s tuning into your body: pale-yellow urine means you’re on track, while dark yellow, dry lips, headaches, or brain fog are subtle nudges to top up.

Hydration doesn’t need to be complicated or measured in strict glass counts – it’s about making it a consistent, intentional habit that fits your life. Whether that’s sipping throughout the day, keeping a glass of filtered water by your bed, or finally giving in and buying that water filter jug everyone on TikTok loves, do what works for you. Consistency over volume is the real game-changer!

Did you know 80% of your brain is water, and losing just 1–2% can mess with focus, mood, and energy?

Most Aussies aren’t hitting their personal hydration sweet spot – four in five of us (79%) admit we don’t drink enough water, usually because we just forget.

That’s where BRITA comes in. Filtered water tastes better, removes nasties like chlorine and microplastics, and turns hydration into a mindful daily ritual.

Find out your Hydration Personality and get simple, personalised tips with the Hydration Quotient Quiz.