Watropy is a simple but powerful idea: water has value not only by volume, but by how long it stays useful. In hot, dry climates, most rain is absorbed before any runoff begins, so dams often rely on rare big storms. Watropy reframes the “water crisis” as a harvesting and storage problem, not just a rainfall problem. It points to practical solutions—storing water locally, storing water in soil, and using systems like wicking beds and percolation holes to extend the useful life of every drop.
In a drought, or under climate change, the soil dries out. The first consequence is easy to miss: when dry soil receives rain, it acts like a sponge. Before there is any meaningful runoff, the ground must be rewetted. In this model, about 50 mm of rainfall is needed before water starts to move across the surface and flow into waterways and dams. This is one reason that conventional dams, which work well in cold and wet climates, can be poor water-harvesting tools in hot, dry climates.
A dam can look like the logical answer, but the dam’s catchment is only a small percentage of total land area, and even within the catchment we only capture a small portion of the rain that falls. After long dry periods, dams can continue to fall even when decent rain arrives, because the soil absorbs the first rain events. The system then becomes dependent on repeated major rainfall events before storage levels recover.
The consequence is a familiar pattern: the dam is drying up, rain comes, but there is no flow into the dam because the water is absorbed by the soil. After the next major rainfall, the dam finally begins to fill. When a water system depends on that sequence, it is not surprising that “crises” appear at the end of extended dry cycles. The shortage is not mysterious. It is built into the way we harvest water.
We Only Catch a Tiny Fraction of the Rain
The watropy argument uses a blunt statistic to highlight the scale of the problem: we only catch about 1 in 2,000 litres of the rain that falls. That is not a comment on a single dam or a single year; it is a way of showing how limited our current harvesting strategy is. If the vast majority of rain either evaporates, is absorbed and later evaporates, or drains away without being stored for later use, then the “water crisis” can be as much a design failure as a rainfall issue.
This is the moment where the paper calls for a paradigm shift. Instead of thinking only in terms of total volume stored behind major walls, we need a way to measure usefulness. We need language and concepts that make it normal to ask: “How long will this water remain useful for the purpose we need?”
From Entropy to Watropy: Measuring Usefulness
In energy systems, engineers think in two dimensions: quantity and usefulness. The usefulness dimension is often discussed through the concept of entropy. High-quality energy can do valuable work; low-quality energy still exists in quantity, but may no longer be useful for certain tasks.
Watropy applies the same thinking to water. Water also has two dimensions: quantity, and useful life. Watropy is a proposed concept to measure the useful life of water. A small volume of water can be extremely valuable if it remains available at the right time and place. A far larger volume of water may exist in the system but have low usefulness if it is not accessible, not stored, or arrives at the wrong time.
The practical meaning is straightforward. If we can extend the useful life of water—by capturing it locally, storing it with low evaporation, and keeping it in forms that can be accessed when needed—we can reduce dependence on rare runoff events. Watropy leads to a different way of designing water systems: not only “how much water can we capture?”, but “how can we keep it useful for longer?”
How Do Paradigm Shifts Get Accepted?
A new paradigm is not accepted simply because it is clever. It tends to begin with dissatisfaction with the old paradigm. In this case, the dissatisfaction is clear: our dams are not providing us with enough reliable water under hot, dry, variable conditions. When people feel the gap between what the system promises and what it delivers, they become open to different thinking.
Watropy is not presented as a slogan. It is presented as a tool for changing decisions. If water can be understood as having useful life, then it becomes reasonable to design systems that harvest smaller rains, store water in the soil, and use biology and landscape design to reduce evaporation and waste.
Wicking Beds: One Example of Watropy
A wicking bed is given as a practical example of watropy because it stores water in the soil and makes it available over time, rather than letting it disappear quickly through runoff or evaporation. The key idea is that water stored below the surface can have a much longer useful life than water left exposed.
The watropy approach begins by noticing something simple: rain that falls onto hard surfaces is immediately available. Roofs, roads, and pavements produce fast runoff because they do not absorb water like dry soil does. This can be crude and inexpensive to capture. The condition is that the water must be stored locally, because the advantage is lost if it is allowed to flow away.
Simple Water Harvesting Surfaces
One basic method shown is to create a water harvesting area by shaping a sloping bank with flow grooves. The surface can then be covered with plastic sheeting to direct the water, and finished with stones. The concept is not complicated: guide water where you want it to go, reduce losses, and keep the storage close to where the water is needed.
This is where watropy starts to feel practical. A small fall of rain can become more useful if it is concentrated, directed, and stored instead of being scattered, absorbed, and evaporated with little benefit.
Water Tanks: Useful, But Not the Whole Answer
Water tanks are described as an effective way of storing household water. They are familiar, reliable, and easy to understand. However, tanks are also described as too big and too expensive to store the volumes required for irrigation. This is not an attack on tanks; it is a reminder that gardens and food production require a great deal of water, and that storage needs to be matched to the purpose.
The alternative proposed is direct: store water in the ground. The document makes a strong point that there is more water stored in the soil than in all our dams combined. If that is true, then soil is not just the medium plants grow in—it is also a major storage system. Watropy thinking pushes us to design soil and sub-surface storage as deliberately as we design tanks.
How a Wicking Bed Stores Water in Soil
A wicking bed stores water in the soil through a simple structure: a plastic liner forms an underground water reservoir. Water is held below the soil surface and wicks upward to irrigate plants. The benefit is twofold. First, evaporation loss is reduced because the main body of water is not exposed. Second, water is delivered where plants use it—near the root zone—over time.
In watropy terms, the same litre of water stays useful for longer. It is not simply “applied” and then lost; it is stored and metered out by capillary action and plant demand.
Grey Water and Cascading Wicking Beds
The watropy slides also describe grey water suitability. Wicking beds can cascade, with water flowing from one bed to the next. This makes them suitable for grey water systems where water is reused and progressively cleaned and stabilised as it moves through the system.
The document notes that worms in the early bed help purify the water for later beds. This is an important point because it shifts “treatment” from a purely mechanical or chemical idea to a biological one. In the watropy worldview, biology becomes part of the infrastructure. The beds are also described as more suited to shallow-rooted plants, which fits the idea of using them as productive systems for vegetables and similar crops.
Watropy Schemes: Practical Designs for Real Landscapes
The final section presents a set of watropy schemes—practical patterns for capturing, storing, and extending the useful life of water. These are not framed as perfect answers, but as examples of how the new paradigm can be expressed in physical form.
Wicking Bed with Rain Amplification
One scheme is a wicking bed with rain amplification. The core concept is to increase how much useful water reaches the bed by directing rainfall into the storage zone. In practice, this is often done by shaping catchment surfaces and directing runoff into the bed area, turning small rains into meaningful soil moisture.
Wicking Bed Pipe-Fed from a Tank
Another scheme is a wicking bed fed by pipe from a tank. This integrates the strengths of tanks (reliable capture of roof runoff) with the strengths of soil storage (low evaporation and sustained delivery). The tank can provide water when rain is absent, and the bed can hold that water in a form that remains useful for longer than surface watering.
Percolation Holes for Deep-Rooted Plants
Percolation holes are described as more suited to deep-rooted plants. A key detail is that water at the bottom of the hole is under pressure and so inflates a large volume of saturated soil. This is a different storage geometry: instead of a shallow reservoir feeding shallow roots, the water is pushed into deeper soil volumes where deep-rooted perennials can access it. This again is watropy in action—placing water where it stays useful for the target plants.
Leaky Dams and Soil Saturation
Another scheme describes water in a lower catchment dam being pumped to an upper “leaky” dam which saturates the soil. The key idea is to use the landscape itself as storage. Rather than keeping water only as open surface storage, the system intentionally saturates soil volumes, where water can be retained with lower evaporation and can support vegetation and productive land use.
Conclusion: A Better Water Logic for a Hotter, Drier World
Watropy reframes the water problem. It says we cannot judge success only by how many litres we store in big structures, because usefulness matters. In hot, dry climates the first rains disappear into dry soil, and dams become dependent on repeated major storms. If we only catch a tiny fraction of the rain that falls, then harvesting and storage strategy must change.
The watropy approach points to practical alternatives: capture water locally from hard surfaces, store water in soil, use wicking beds to extend water’s useful life, cascade beds for grey water reuse, and use percolation holes and leaky-dam soil saturation to support deeper-rooted systems. These are examples of a paradigm shift that treats water as a resource to be kept useful—not just collected.
Download “Watropy – The Paradigm Shift in Water Thinking” (full PDF)
