I love looking at landscape design in more simple ways, the idea of stepping out of the constant fight with nature and instead observing, learning from, and working alongside it. It’s a grounded approach. And if that mindset is the foundation beneath how I design, then Rainwater Harvesting for Drylands and Beyond by Brad Lancaster is one of the key resources that has shaped how I think about water, how to slow it down, spread it out, and make the most of a resource that quite literally falls from the sky.
Rather than give away the entire book, I’ve put together this guide to walk through eight core principles of rainwater harvesting. These ideas align closely with regenerative design thinking, and more importantly, they’re practical. They can be applied to just about any site and serve as a strong foundation for creating landscapes that are both functional and resilient.
1. Begin with Long & Thoughtful Observations
For those who’ve read the Permaculture Designer’s Manual, this one will sound familiar, and it’s beautifully simple: observe.
Pull out an umbrella and stand in the rain. Watch how water moves through the site. If you live in the city or have downspouts, notice how water exits them. Does it pool anywhere? Does it race away? What do the trees look like, bent from wind, or standing straight as an arrow?
Use all your senses: sight, smell, touch, hearing… even taste, if you’re brave. Things to look for include:
- Bare spots where water is eroding soil
- Lush greenery that signals something is working
- Running water, and how fast it’s moving
- Polluted areas (trash and debris washing in from streets)
- Hard-packed or washed-out soil
- Signs of life: birds, insects, dragonflies, many never stray far from water
- Average rainfall for your area
- Evidence of erosion, and where it’s coming from
Most importantly, don’t get tunnel vision. Always remember the site as a whole.
Ask yourself: If I change something here, what happens over there? If you redirect water in the backyard, does the front yard suffer? If you create a dry creek from front to back, are plants now struggling with reduced moisture?
All of this can (and should) be worked out in your head before a shovel ever hits the ground, eliminating big mistakes before they ever occur. And yes, harmless self-plug: this is exactly why thoughtful design matters.
2. Start at the Top (the High Point) of Your Watershed and Work Your Way Down
I love this one. Again, simple.
Start at the highest point of the property. That’s where gravity is doing the most work for you. From there, move downslope.
Before jumping straight to a rain garden at the lowest point of your site, ask yourself:
Can I slow the water uphill first?
Could a berm or subtle earthwork intercept and spread that water more efficiently before it ever becomes a problem below?
Because if you build the rain garden first, miscalculate its size, even a little, and it still doesn’t solve the issue… you’re in a real pickle. It’s far safer (and smarter) to move gradually downhill, stacking small solutions and letting gravity guide you rather than betting everything on one big fix at the bottom.
But think bigger than just your property. This whole beautiful planet is essentially a quilt of watersheds. Understanding where your site sits within one helps you understand where water is coming from, and where it’s going.
Side note: below is a killer video by Andrew Mollison if you wanna watch how to find your watershed.
When rain falls faster than the earth can absorb it, surfaces become overwhelmed. Water cascades over roofs, roads, and compacted soil, sweeping everything downslope in its path. This powerful movement is called runoff.
The further down you are in a watershed, the greater the runoff volume. The steeper the slope, the faster it moves. Gravity is relentless, and kind of amazing. (Don’t tell a flat-earther.)
The goal of rainwater harvesting is simple: get that water to soak in, to infiltrate the soil, recharge life, and regenerate the landscape.
Unfortunately, most cities are designed to get water off the land as fast as possible. Streets funnel it into sewers, where it’s whisked away and eventually pumped back into our water supply. That’s… not ideal. And just remember if you begin to harvest water high in the watershed and work your way down, you’ll make everything easier in the long run because:
- The volume of runoff you deal with at any one time will be less and more manageable
- You can use many modest-sized structures instead of one massive system
- Vegetation gets watered without being flooded
- Rain infiltrates evenly throughout the landscape, not just at the bottom
- Water harvested high can be moved more easily using gravity, a free and ever-present energy source
3. Start Small & Simple
This principle piggybacks directly off the last one.
Work from top to bottom, and start small instead of large.
Rather than building one giant structure, think in terms of many small, human-scale interventions. Tiny water-harvesting pockets are easier to build, easier to maintain, and far more forgiving than one massive system.
As Lancaster puts it (and I love this):
“If a small mistake is made, it will teach you – not break you.”
Small systems let you learn, adapt, and improve without catastrophic consequences.
4. Spread and Infiltrate the Flow of Water
Another nice and easy one that can be summed up with – spread the water so it flows, not runs. We want infiltration, not erosion. This is a strong argument against concrete channels and hard edges.
Think of the land as a wide net. The wider the net, the more water you catch. Slow it down, spread it out, and let the soil do what it’s meant to do.
5. Always Plan for an Overflow Route, and Treat Overflow as a Resource
So now imagine you’ve cast your wide net. You’ve installed rain barrels, cisterns, or catchment systems. Time to ask yourself: what happens when they overflow?
Overflow isn’t a waste, unless you fail to plan for it.
Every tank, cistern, or rain garden should have an outlet directing excess water to a useful place: a vegetated basin, a tree, a shaded planting area that provides food, habitat, and cooling.
Pro tip: Always try to end in a vegetated wash or creek.
A vegetated wash, natural or engineered, is simply a channel lined with plants. These areas filter pollutants, slow water, improve infiltration, and dramatically reduce erosion.
6. Maximize Living and Organic Groundcover
Remember above how I asked you to lookout for bare soil? This is why.
Bare soil becomes compacted, seals off moisture, and creates runoff instead of absorption. Living groundcover, on the other hand, acts like a sponge, what the book beautifully calls “a welcome mat for water.”
Roots combined with surface mulch transform the landscape into a living sponge. This combo can more than double stormwater infiltration while reducing evaporation, erosion, runoff, and even mosquito breeding.
Especially valuable knowledge for those of us living in the heat of Hot-Lanta.
7. Stack Functions
This one will feel very familiar to permaculturists.
A good design never does just one thing. A tree isn’t just a tree, it’s food for people, habitat for wildlife, shade for a home, cooling for the landscape, and a sponge for water.
We stack function upon function, connecting systems so each element supports another. Companion planting is another example, blueberries paired with yarrow, each building soil health and nutrient availability.
If one solution solves multiple problems and creates more resources in the process, you’re doing something right.
8. Continually Reassess Your System (The Feedback Loop)
Last but not least: the job is never done.
Low-maintenance never means no-maintenance. Landscapes evolve. Systems change. What worked this year might need adjusting next year.
Keep observing. Stay flexible. Designing in zones helps. Continually reassess and adapt, always returning to these principles.
The goal is simple: to serve not only ourselves, but the greater good, by working with nature, never against it.
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