Today I will compare bringing a flask to buying drinks from shops. The result might be pretty obvious for some of you, but it might be news to others.

Since I was a kid, I have used a vacuum flask to bring iced cold tea to school, especially during the summer in Japan. And I’ve mostly kept at it ever since. Well, storytime is over; let’s have a look together!


THERMOS 4035.211.075 Ultralight Thermos Flask, White 750 ml


Flask: £20 to £25 for 500ml.

Tea: 100 tea bags-> £5 = 5p per tea bag

Coffee: 1 bag of grounded coffee-> £5 = roughly 30p per 500ml of dripped coffee.


  • You can prepare your favourite, which is much cheaper than buying it from shops.
  • It generates less waste.
  • It keeps the drink hot or cold for long hours.


  • You need to spend some time preparing your drinks.
  • Some people might think it’s troublesome.
  • Not ideal if you’re in a rush.

Drinks from coffee shops


£3 to £5 per drink


Fresh, made by professional staff.


More expensive and more waste of cups and lids.


We love using flasks and bringing them with us. Typically we use the 500ml capacity; it’s great for a day out. We can drink whenever we want, and we don’t need to find a bin to throw rubbish.

When we drove through France, I was happy to have them. Generally, whatever is sold in a service station is more expensive than in usual shops. We carried one for coffee, another for hot tea, and a stainless steel bottle with cold-brewed tea for the two of us. Therefore we didn’t need to buy any drinks!

Another good thing about the Thermos is that we can keep the temperature longer. I am a slow drinker, and most of the time, when I serve coffee in a mug, I end up with cold coffee halfway through. Then I remembered that my mother used to make coffee and keep it in a large Thermos for everyone to have during the day. So now, when I am having coffee, I pour it into a flask and have a hot coffee anytime I want. Of course, I don’t need to reheat, so it saves some (a little) energy!

Result: Flask, ftw!


We get coffee five days a week to bring to work or school.

I usually prepare an americano for myself, and buying a large americano (between 450ml ~ 500ml) from a coffee shop in England is around £3.

One coffee: £3

Weekly: £15

Yearly: £810 (£726 if you don’t count holidays)

((3*5)*54)-(3*28) = £726

On the other hand, if you make your coffee at home and bring it with your flask, the first investment is £25, then making roughly 30p coffee, but let’s say it’s 50p for the energy cost.

One flask: £25

One coffee: 50p (includes ground coffee & energy cost)

Weekly: £2.5

Yearly:  £135 (£121 if you don’t count the holidays)

(0.5*5)*54 = 135

((0.5*5)*54)-(0.5*28) = 121

Even if we add up the cost of the flask for the first year,  it’s still much cheaper than buying a cup of coffee from a shop. I have been using mine since the winter of 2020, so it’s been more than a year, but I’ve not had any problems, and I am sure that I can use it even longer.

THERMOS 4035.211.075 Ultralight Thermos Flask, White 750 ml

Closing words

Sometimes it’s annoying to make your drink. It doesn’t need to be every day. Using your reusable bottles instead of buying them makes a difference in your waste and money. Or bring your bottle to a shop to fill it; they often offer a discount. I don’t see any problem with reusable bottles.

We talked about eco and budget-friendly products for three posts in a row, but the next blog post is back to recipes! I will continue to look for eco and budget-friendly products and share them with you guys!

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