A reusable bottle versus plastic bottles: counting money and counting waste

Everyone knows a reusable bottle beats plastic environmentally. But "good for the environment" is vague and rarely shifts behaviour. The numbers are clearer — and the most persuasive one turns out to be money.

Counting money

Say two small bottles of water a day at roughly 5,000d each from a convenience store.

• A day: 10,000d
• A working month (22 days): about 220,000d
• A year: about 2,600,000d

A decent insulated steel bottle costs somewhere between 200,000d and 400,000d. That means it pays for itself in one to two months, and everything after is money saved.

The figure is striking because it contradicts the feeling: the bottle seems expensive because you pay in one lump, and plastic bottles seem cheap because you pay in dribs. But the dribs add up to far more.

Counting waste

Same assumption: two bottles per working day.

• A month: about 44 bottles
• A year: about 530 bottles
• A 20-person office: over 10,000 bottles a year

One person's number sounds small. Multiply by an office floor and it's a mountain.

And plastic bottles aren't recycled automatically — they have to be sorted and collected properly, and small half-drunk bottles thrown in with general rubbish end up in landfill rather than a recycling plant.

Why people buy a bottle and abandon it

More practical than the arithmetic. Bottles get abandoned for quite specific reasons:

• Heavy and bulky. A full 1-litre bottle weighs over a kilo. Carrying that all day in a small bag is a nuisance. 500ml is more realistic for anyone on the move.
• Annoying to wash. Narrow-necked bottles can't be reached into and develop a smell. Choosing a wide-mouthed one from the start avoids most of this.
• Forgetting it. The most common reason, solved by habit: keep it next to the bike keys, or keep a second one at work.
• Nowhere to refill. No water cooler at work makes the bottle useless. Worth checking before buying.

In other words, bottles fail because of the wrong bottle or no refill point, rarely for lack of willpower.

Choosing one

Refilling: the part people don't count

One more factor rarely included: where the water comes from.

• The office cooler — free to the user, and the reason a bottle pays back fastest at work.
• A 20-litre jug at home — far cheaper per litre than small bottles, and the container is returned and reused rather than becoming waste.
• A tap filter — costs both to install and to replace cartridges, so it's worth it for a household, not for one person.

The common thread: all of them are cheaper per litre than small bottles. Small bottles are expensive not because of the water but because of packaging and transport — the part that becomes waste.

Washing

An unwashed bottle smells, and a smelly bottle gets abandoned. Three things are enough:

• Rinse daily rather than topping up over yesterday's water.
• Wash properly every few days with warm water and a little baking soda if a smell starts.
• Leave it upside down to dry fully before closing the lid. Capping it damp is the main source of smell.

The wider point

A reusable bottle is one of the few "green" habits that benefits the person immediately rather than being a sacrifice for the common good. Real money saved, and nothing further to buy.

In the same category: bringing a container for takeaway food, and bringing a cloth bag to the market. Those three together cut daily waste more than grander-sounding efforts that last a few attempts.

Quick answers

How fast does a reusable bottle pay for itself?

One to two months, if you were buying two small bottles per working day. Plastic looks cheap because you pay in dribs, but it adds up to around 2.6 million dong a year.

How many plastic bottles does one person save?

About 530 a year at two per working day. A 20-person office is over 10,000 a year.

Why do people abandon their bottles?

Four specific reasons: too heavy, annoying to wash because of a narrow neck, forgetting it, and no refill point at work. Mostly the wrong bottle rather than a lack of willpower.

What size should I get?

700ml to 1L for a desk; 500ml if you're on the move, since a full litre weighs over a kilo and is a nuisance to carry all day.

Where's the cheapest place to refill?

The office cooler is cheapest for the user; at home a 20-litre jug is far cheaper per litre than small bottles and its container is returned and reused. Small bottles cost more because of packaging and transport, not the water.

How do I stop the bottle smelling?

Rinse daily, wash properly every few days with warm water and a little baking soda, and leave it upside down to dry fully before capping — capping it damp is the main cause.