A quick look at the map of France is enough to see just how much water has become an object of desire. Far from alarmist rhetoric, official figures paint a very real picture—one that challenges citizens and local authorities alike:
- A shrinking resource: Water availability could decrease by 10% to 40% in the coming decades (Source: Vie Publique, 2023).
- Intense droughts: A recent winter recorded 32 days without rain—a record that weakens our reserves.
- Fragile reserves: In early 2023, 80% of groundwater tables were at a low or very low level.
In this context, the idea of a home that can sustain itself is no longer a “survivalist” fantasy, but a credible technical horizon. Yet independence cannot be decreed. It requires understanding the water cycle, complying with a strict legal framework, and adapting your uses with solutions such as Infinit’O.
Why is water self-sufficiency becoming urgent?
The question has changed its face. It’s no longer just an environmental wish—it’s a rational response to two major pressures:
1. Climate pressure and the state of the network
The State no longer hides how fragile the system is. The government plan targets 10% water savings by 2030 to prevent shortages. Even more worrying: about one liter of drinking water out of five is lost through leaks in distribution networks before it even reaches the tap. Total dependence on the public network is less reassuring than it used to be.
2. Economic reality
Water costs are rising. With an average consumption of 145 liters per person per day (i.e., 53 m³/year), the bill weighs heavily—especially in the South, where pools and heat push the numbers up (Source: National Observatory of Water Services). Controlling your supply also means controlling your budget.
Understanding what being “self-sufficient” really means
Beware of simplistic promises. Self-sufficiency isn’t a single on/off state—it’s a scale of progress:
- Partial self-sufficiency (the most common): It aims to cover non-potable uses (toilets, laundry, watering) with an alternative water source, while keeping the mains supply for cooking and drinking. This is the most pragmatic way to start.
- Total self-sufficiency: This means using only the water collected on your property (capture, storage, full treatment). It requires rigorous management and precise sizing.
- “Systemic” self-sufficiency: A global logic where water, electricity, and heating are designed together for a resilient home, inspired by biomimicry.
⚖️ What the law says (Decree of 12 July 2024)
The framework is strict: only rainwater collected from inaccessible roofs (without asbestos or lead) is authorized for domestic uses. Use is allowed for toilets, floor cleaning, and—under conditions—washing machines. Any connection between the rainwater network and the drinking water network is strictly prohibited to prevent contamination of the public network.
Read the full decree on Légifrance
Capturing rain: the first pillar of self-sufficiency
Rain is the most accessible resource. The calculation rule is simple:
1 mm of rain = 1 liter of water per m² of roof area.
Example: A 100 m² roof in Western France (800 mm/year) can theoretically capture 80,000 liters per year (Source: Météo France). That’s huge—but it requires a reliable technical setup, far from a simple barrel under a gutter:
- Catchment surface: A clean, sound roof.
- Pre-filtration: A “settling” device to remove leaves and debris.
- Storage: A tank (concrete or polyethylene) sized to your real needs—not chosen at random.
- Distribution: A pump and a management system to switch to mains water if the tank is empty.
Groupe O expertise: This is where we come in. Rather than selling a standard kit, we act like a conductor. We analyze your local rainfall and your consumption to create a coherent, durable, and hygienic system—far from DIY setups that don’t stand the test of time. Discover our approach to rainwater harvesting.
Filtering and treatment: from raw water to household water
Collecting water isn’t enough—you have to make it suitable for its intended use. The decree of 12 July 2024 defines the required filtration levels:
- For the garden and toilets: Mechanical pre-filtration (50 to 100 microns) is generally sufficient.
- For the washing machine: Fine filtration is essential to block particles and protect the machine.
- For making it drinkable (outside the standard framework): Some households use ultrafiltration or reverse osmosis + UV to drink rainwater. Warning: once you make the water potable, you leave the simplified framework and assume responsibility for the health safety of the water you produce.
Health reminder: ANSES recommends caution for laundry belonging to vulnerable people (young children, immunocompromised individuals) and stresses regular filter maintenance. Sustainable self-sufficiency is monitored self-sufficiency.
Which uses can you realistically cover?
No need to aim for everything right away. Focus on the most water-hungry uses. It is possible to replace around 50% of a single-family home’s drinking water by targeting three key areas:
- 🚽 Toilets (a major, unnecessary consumer of drinking water).
- 👕 The washing machine (with appropriate filtration).
- 🌻 Garden watering (the category that spikes in summer).
Data based on national average consumption (Sources: ADEME, CIEau 2024). The substitutable share varies depending on rainfall and outdoor uses.
Out of 145 liters/day, half can come from the sky. That’s an immediate impact on your bill—and on groundwater reserves.
The full loop: don’t forget wastewater treatment
Talking about water self-sufficiency without mentioning wastewater treatment is inconsistent. What happens to the water once it’s been used?
To be coherent, the system must close the loop. Autonomous wastewater treatment solutions (such as constructed wetland treatment or sand filters) make it possible to treat wastewater on site. That’s the philosophy behind our solution at Inphyto: combining harvesting and treatment to preserve soil quality and waterways.
Conclusion: Myth or reality?
Water self-sufficiency isn’t a myth—it’s a demanding technical reality. It’s possible, as proven by hundreds of pioneering households in France. But it’s not a magical “plug-and-play” solution.
It requires:
- An initial investment (tank, pump, works).
- Sufficient roof area.
- Regular maintenance (cleaning filters, tanks).
- A shift in behavior toward frugality.
Our advice? Aim for partial, controlled self-sufficiency rather than absolute autarky. Replacing 50% of your consumption is already a huge win for your wallet—and for the planet.
Do you have a rainwater harvesting or wastewater treatment project?
Don’t size your installation at random. Groupe O supports you from the feasibility study all the way to installation.
FAQ – Water self-sufficiency: answers from experts
Can you produce your own drinking water at home?
Yes, technically. But it requires rigorous treatment (fine filtration + UV/osmosis) and constant monitoring. Rainwater is an excellent base, but it cannot be made “drinkable” with a simple under-sink filter. Most households opt for “partial” self-sufficiency (toilets, laundry, garden) to avoid health risks.
Does water autonomy consume a lot of electricity?
No. Energy is mainly used for the distribution pump (booster). In a well-designed system, consumption is minimal and can be covered by a few solar panels, as in our autonomous natural pool solutions.
Is this a topic reserved for expert DIYers?
It is accessible to everyone, but it is not a “do-it-yourself” job. Given the health and regulatory issues involved (separation of networks), installation must be carried out by professionals or highly knowledgeable amateurs.
Is water self-sufficiency profitable?
If we look solely at the current price per cubic meter of water, the return on investment is long (10-15 years). But if we factor in future increases in the price of water, the increase in property value, and the ability to water when the network is restricted (during droughts), it is an immediate investment in resilience.