Translator: Mary Burke Reviewer: Angelika Lueckert Leon
Water is essential to our lives,
but unfortunately it’s not available in unlimited quantities.
We require quite a lot of water for industry, for household use,
for food production.
If I ask you what you’ve already used water for today,
I’ll probably get similar answers from everybody,
and here’s what you’d tell me:
I took a shower today,
I flushed the toilet several times,
washed my hands, cooked, did the dishes,
used water around the house, did laundry,
also drank some, of course,
and maybe even watered plants in the garden or on the balcony.
That’s quite a lot of water,
which we need every day for each person in the household.
It adds up to 122 liters per day.
But that doesn’t include the amounts of “virtual” water
that we need to produce food
or manufacture clothing.
Let me give you an example.
Who here has had a cup of coffee today?
I’d say that’s quite a few.
I’ve had some coffee today too.
And to produce one cup of coffee,
you need an average of 140 liters of water.
That’s quite a lot.
To make one pair of jeans, for example,
it takes 8,000 liters of water.
If we look at the global picture,
if we look at ourselves in the context of the world’s population,
here’s what we see: There are currently 7.9 billion people living on earth
and the population is still growing.
That means we need more and more water for the things we use it for.
This will inevitably lead to water scarcity at some point.
And we may already be there.
If we look at the global availability of water resources,
it breaks down like this:
97.5% is salt water
and therefore 2.5% is fresh water.
Looking at the amount of fresh water, which we mainly use,
the fact is that roughly 70% isn’t even usable to begin with
because it’s locked up in glaciers and so on.
The water we do use, the groundwater or surface water,
this small amount that makes up some 30%,
will therefore have to be shared by more and more people.
This is the situation we’re dealing with at present,
and then there’s climate change on top of that.
We have to get through drought periods-- more and more of them worldwide.
We have to irrigate fields
so that we can maintain land productivity.
That’s essential no matter what,
and water scarcity will continue to be a concern for us.
You’ve seen images from California, China, India.
That’s all very far away.
People currently assume
that this kind of thing won’t ever happen in Germany.
But generally speaking, the fact is
that roughly half the world’s population experiences temporary water scarcity.
And we assume
that this kind of thing is still a long way off in Germany,
that this kind of thing won’t happen.
However, there was a situation last year
where water stopped coming out of faucets,
and it happened in a community in Lower Saxony.
As a matter of fact, 4,000 people were affected by it.
The fire department supplied firefighting water,
which was offered to residents to use for flushing toilets.
Drinking water, however, had to be bought at the supermarket.
Let’s go back one more year, to 2019.
Maybe you remember the articles
that made the rounds in the media all over Germany.
They said that citizens were supposed to water the trees.
This was in Weinheim.
And then this one from Berlin.
Citizens were supposed to water the trees.
And in the Ruhr district as well, the citizens were asked
to water the street trees themselves.
At about the same time, there was an article from Hesse.
Drinking water was already running low there.
One month later, a headline in the “Frankfurter Allgemeine Zeitung”
asked that people please not ater city trees with drinking water,
since drinking water is a food item and too valuable to use for watering,
especially in times of drought.
Watering may be a necessity,
but ultimately it will have to be done differently than it has been up to now.
What this means is that we need new strategies
for opening up alternative water sources,
and securing the water supply.
What can be done about this? What kind of plans are there?
What are you already doing at home?
I’m sure some of us have a rain barrel in the yard
or a cistern, and you collect rainwater
and then use it in your garden.
But here’s the thing about rainwater:
We don’t know when it’s going to rain, or how much.
It’s inherently a highly unreliable source of water.
It’s rained a great deal this year.
You probably didn’t even have room to store all the water,
there was so much rain.
Last year it was the exact opposite.
It didn’t rain much then,
and it was barely enough to get through those long dry spells.
And so we need more sources, more water sources
that we can count on every day.
What could that be?
Maybe it’s this.
Wastewater.
Maybe not at that level of quality,
but here it looks much better.
The special thing about wastewater is: We can really plan around it.
We know what gets processed at a sewage plant
and that water can be treated
according to the “fit-for-purpose” principle.
So it can be processed appropriately for a particular use.
Because we in Germany afford ourselves the luxury
of actually using potable water in every situation where we need water.
That is inherently totally unnecessary.
I’d like to show you an example from the USA.
Green spaces and lawns are often watered with reused water over there.
There’s even an advantage to this, when we look at it,
when we go back to the fit-for-purpose principle,
then nutrients can stay in the water,
like nitrogen or phosphorus,
meaning, you also get a fertilizer effect at the same time--
so even more positive effects that come along with it.
I also don’t need potable water to flush the toilet.
I don’t want to drink it, after all--
instead, I’m going to turn it directly into wastewater,
which means that lower-quality water would suffice.
Of course, it’s possible technologically to turn wastewater into drinking water.
Singapore does it, for example.
Drinking water is produced here.
Singapore is a trailblazer in this area,
but of course there’s also the question of water stress in a given region,
and also costs.
Those things have to be seen in relation to each other,
and consequently need to be taken into account.
And of course, if we can produce water,
if we can make drinking water out of wastewater,
then of course we can brew beer too.
Two years ago, this beer--
the last International Water Reuse Conference was in Berlin in 2019,
they provided this beer every evening, brewed from Berlin wastewater.
And I can tell you,
it messes with your head, having a bottle of that in your hand,
but... I enjoyed it, and I’m still here,
so it was totally fine to drink.
Now there’s just one question we need to ask.
When we talk about reused water, about implementation,
we have to ask ourselves an important question:
How does this water get to the user in the first place?
The answer is simple for beer or water.
I could sell it in the supermarkets and buy it there,
but if I’m thinking about irrigation or flushing toilets,
then there has to be an infrastructure solution.
I’d like to show you an example from California.
The city of Irvine was planned in the 1960s.
It’s a city that was planned on a drawing board.
They included a reused water distribution system in their plans
alongside the drinking water supply.
Of course it’s also a great solution for watering green spaces.
It’s used to water 90% of all the green spaces in Irvine.
And so the city is very green,
and what they call the “purple pipes” are this recycled water system.
This concept doesn’t transfer quite so easily to Germany,
because we rarely plan for green-field development any more
due to densification trends, the 30-hectare land take target.
And so a solution for existing settings, planning in existing settings,
isn’t quite so simple here.
But there are also approaches we can think about.
Another example from California: San Diego has set up filling stations
where residents can get recycled water like at a gas station,
and take it home to water their gardens.
Those are solutions that could also be feasible in Germany.
It’s also been done in Santa Barbara.
Here’s a map showing the various locations
where people can get water.
So that’s also a potential solution for Germany.
During my research
I came across an interesting article from the city of Stuttgart.
In 2020, so last year,
Stuttgart bought new watering trucks to water the city trees.
10,000 trees get watered in Stuttgart.
That takes 90,000 liters of water.
So of course you might ask: Why don’t we use this kind of water now,
and then water the trees with it
and solve a problem that way?
If we had those filling stations it would be even more efficient.
Another example I’d like to show you
is a little bit of reuse within the home,
which you can think of as a household solution.
This is an example from Japan, a vacation rental I visited years ago,
I found it really interesting.
You wash your hands, the water goes right into the toilet tank,
and then you use it to flush.
It doesn’t take up much space,
it’s relatively cheap,
so it’s an option that you could use right in your own home.
It can be even simpler,
for example, if you take the water you just rinsed the lettuce with
and use it, don’t pour it down the drain,
but pour it into the rain barrel instead, or a watering can,
and then put it right on your garden or your balcony plants.
A solution that anybody can start with tomorrow morning, pretty much.
But let’s go back to the bigger picture.
What we can save personally is just small amounts, of course.
If we look at the city of Stuttgart,
with about 608,000 inhabitants,
and if we look at the 122 liters of water
that we use in a household,
then the amount of wastewater comes to
over 74 million liters generated per day--
which we could plan around.
Compare that to the 90,000 liters that we need for 10,000 trees,
it’s only 0.12% of that.
That means that we still have 99.88% available to use.
So, we could be doing much more with it,
like watering VfB Stuttgart’s soccer pitch.
There would still be a pretty large amount left over--
99.86%.
We can keep the game going and think about what would happen
if we watered other land this way: private, public.
And so, this is what I’m asking cities to do:
Set up water filling stations,
water your green spaces with reused water,
because it will make the cities greener,
both horizontally and vertically,
and set up those filling stations for your citizens.
And what I’m asking you as citizens:
If you’re offered this option someday,
and I hope you will be,
don’t be afraid to take it, go for it.
There’s nothing bad about coming into contact with it,
even potentially drinking that kind of water at some point,
when its quality level is “fit for purpose.”
Thank you.
(Applause)