A Simple Way to Save a Billion Litres of Water Per Year in the Pyrénées-Orientales — And Save Households €30
The Pyrénées-Orientales is one of the most beautiful corners of France, but it is also one of the driest. Our département has lived through repeated droughts, shrinking reservoirs, stricter water restrictions and a future that only promises more pressure on our precious resources.
So here’s a surprisingly simple question:
What if we could save over one billion litres of drinking water every single year — without changing our habits, without discomfort, and without spending money?
It turns out we can.
And the solution fits in your hand.
The Cistern Bag: Small Object, Huge Impact
Most toilets in older homes still use 6–9 litres of water every time we flush. Yet, most of that volume isn’t needed. A cistern displacement bag (often called a cistern bag or water-saving bag) is a small, durable pouch that sits inside your toilet cistern and reduces the volume of water released during a flush.
How much water does it save?
1–2 litres per flush
Around 4–8 m³ per year per household
Saves €17–€34 per year, based on local water tariffs for each household
You simply place the bag inside the cistern, close the lid and forget about it. The toilet works exactly the same. No behaviour change. No plumbing skills. No downside.
Simple, cheap, effective.
A Billion Litres Saved in the Pyrénées-Orientales
Let’s do the maths.
Our département has roughly 493,000 residents, meaning about 220,000 households.
If each home saved an average of 6 m³ per year by using a cistern bag:
220,000 households×6 m³=1,320,000 m³ saved220,000 \text{ households} \times 6\text{ m³} = 1,320,000\text{ m³ saved}220,000 households×6 m³=1,320,000 m³ saved
That’s 1.32 billion litres of drinking water.
Every. Single. Year.
Equivalent to:
The annual consumption of an entire medium-sized town
Dozens of Olympic swimming pools
A major buffer against summer drought pressure
All achieved with a tiny piece of plastic that costs only a few euros to produce.
Why Aren’t We Already Doing This?
In France, cistern bags exist, but they’re not widely used, and most people have never heard of them.
Yet in the UK and Ireland, water companies have handed out millions of them for free — because they work.
Given our local situation, perhaps it’s time we adopt the same idea?
Free Water-Saving Kits for Every Household in the 66? Why Not?
Every commune in the Pyrénées-Orientales has a Mayor and every Mayor already communicates with residents: via the Mairie, local newsletters, public announcements, and village events.
Distributing cistern bags could be straightforward:
The Département or Region bulk-buys tens of thousands.
Each Mairie hands out one per household (or mails them with the annual water notice).
Installation takes 10 seconds.
Water savings begin the same day.
Cost to households: €0.
Annual savings per household: €30 or more.
Annual savings for the environment: enormous.
This is the kind of local, visible, universally beneficial action that creates real climate resilience. It is simple, democratic and immediately measurable.
Should It Be Compulsory? An Idea for Local Law
Given the extreme drought risk in our département — and the accelerating effects of climate change — it is reasonable to ask:
Should the Pyrénées-Orientales introduce a local rule requiring all toilets in older properties to use a cistern bag or equivalent device?
We already accept:
mandatory low-energy light bulbs
mandatory insulation standards
mandatory recycling
mandatory controls on watering gardens
Why not a compulsory water-saving measure that costs almost nothing and affects nobody’s lifestyle?
Such a law could apply only to:
Older homes with high-volume cisterns
Rental properties
Buildings using more than a set number of cubic metres per year
It would be one of the least intrusive environmental laws ever passed — and one of the most effective.
UPDATE:
I sent this idea to the Perpignan administration and they responded:
“The Perpignan Méditerranée Urban Community, which is responsible for water and sanitation, has been distributing kits for several years that include ‘eco toilet bags’ as well as attachments for sinks, shower heads, etc., during events held in local municipalities.
In Perpignan, for example, we distributed these kits during the Nature Festival last May, and we will certainly repeat the initiative at new events in 2026.”
Responsable Transition Energétique et Développement Durable, Ville de Perpignan
My Feedback:
It’s wonderful to know that this is underway.
Another excellent step would be for the government to install this system in public buildings, such as schools, police stations, universities, fire stations, and other administrative buildings. That would make a real difference.