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Design: Tina Tiller
Design: Tina Tiller

SocietyNovember 19, 2023

One simple trick to save millions of litres of water a year

Design: Tina Tiller
Design: Tina Tiller

It sounds like a scam, but it’s not. There’s an easy way New Zealand can save millions of litres of clean, fresh water without digging up pipes, messing with lakes or spending an extra dollar of taxpayer money.

Rather than drain our lakes, replace our pipes (though, Wellington, c’mon), hire a cadre of pricy consultants, I suggest simply redesigning one tiny part of our toilets. In North America, that part is called the handle. Here, it’s a “dual flush cistern button”.

An American style toilet.
A North American toilet handle.
A New Zealand style toilet flush button.
A New Zealand style dual flush cistern button.

Despite its cumbersome name, the New Zealand way is good. Most of our toilets allow us to trigger a full flush of four-and-a-half to six litres of water only when we need it. Most of the time, we use a partial flush of roughly three litres. That’s a significant water saving. And as our planet heats and dries, ever more essential.

Note: Most toilets in Auckland use around seven litres per flush and older toilets use around 12 litres per flush, which is partially thanks to many still being single flush.

But there’s a problem with the dual buttons. For new residents and overseas visitors (and yes, for some locals), it’s sometimes hard to tell which button is which. Like this one:  

A confusing toilet buton.
A confusing toilet button (Photo: Effin Older)

Or this one:

Another confusing toilet flush button.
More confusing toilet flushing options. (Photo: Effin Older)

Or this:

A third confusing NZ toilet button.
A third confusing NZ toilet button. (Photo: Effin Older)

It’s just too easy to press the wrong button, and every time we do, we’ve wasted between one-and-a-half and three litres of precious water. Senselessly sent it sailing out to sea. 

And if we get confused by our toilets, imagine how head-scratching they are to visitors from overseas, especially handle-countries. Think of how much water they unknowingly flush away while they’re here.

This ain’t small bikkies. According to the World Toilet Organisation (WTO), the average Earthling uses a toilet six to eight times a day; that’s 2,500 times a year. 

Toilets are our water hogs. A quarter of our household water usage is via the toilet. The average New Zealander flushes 86 litres per day.

That’s us; how about our visitors? According to Tourism New Zealand, last year 1.1 million overseas visitors holidayed here. On average, they spent 17 days on our shores. 

But wait, there’s more. That 1.1 million doesn’t include cruise ship passengers. Jacqui Lloyd, CEO of New Zealand Cruise Association, estimates 360,000 passengers and 149,000 crew will arrive next year. Their ships will make 1,050 port calls.

If each of our visitors flushed six times a day, and half of them got half those flushes wrong, the number of wasted litres sent out to sea would define deluge. An unnecessary deluge.

Unnecessary, because there’s a painless fix. It goes like this:

The prime minister calls New Zealand toilet manufacturers to the Beehive for an urgent meeting. Explains the problem and the solution. “Go back to your offices and come up with buttons that even the most jetlagged tourist can get right.”

The screen behind the PM lights up: “Here are some current buttons that are already working.”

An easy to understand NZ toilet button.
An easy to understand NZ toilet button. (Photo: Effin Older)

And this one:

A toilet flush button clearly demarcated between full and partial flushes.
A toilet flush button clearly demarcated between full and partial flushes. (Photo: Effin Older)

And this:

An example of an easy to understand NZ flush button.
An example of an easy to understand NZ flush button. (Photo: Effin Older)

“The good news is we already have models for what works. Now, we need to figure out how we’re going to make them all work. First step would be to make sure the half-flush buttons are all on the left, the full-flush on the right.”

Any questions?

Does this apply to existing toilets or just new toilets?

To keep it free, just new ones. To achieve maximum impact, both


But not in homes, only public places: hotels, restaurants, museums, stadiums, public restrooms. 

So I won’t have to junk my toilet?

You will not. But when and if you do, your new toilet will be far better for you and the planet than that old one.

Won’t there be resistance to this change?

There’s always resistance to change. But remember, we’re not changing the law, the language, the levels of our lakes — only the little buttons that flush our toilets. 

When should we start?

November 19

What? Why today?

In 2001, November 19 was declared World Toilet Day by 17 toilet associations around the world. World Toilet Day has become a global platform for academics, sanitation experts, toilet designers and environmentalists to swap toilet lore. Then, in 2013, 122 countries co-sponsored a UN resolution tabled by Singapore designating November 19 World Toilet Day as an official UN day.

We have led the world in many things and we can do it again. 

Keep going!