7 Ways to Harvest Rainwater for Your (Permaculture) Garden

In permaculture, it is often thought that ‘planting your water’ is the first step to success. While you may have great soil and a super smart design, if you are neglecting the water flow through your site, you are not only wasting this precious hydration resource, but putting your garden in danger of losing the nutrients you put into your soil and the chance of higher yields.

Rainwater harvesting can help prevent soil erosion while helping you to capture and store rainwater to reduce the need to irrigate your garden. In turn you’ll find yourself saving on water bills and electricity bills associated with pumping water, while seeing your garden flourish and bloom with very little assistance from you; lightening your own workload and helping to raise the water table to assist the surrounding environment.

What is Rainwater Harvesting and Why Do It?

Water is a precious resource, giving life to everything on the planet, including ourselves. One of the key issues currently facing the world is the wide-scale pollution of water resources, causing illness, disease, and mutation worldwide. Not only that, the process of acquiring drinking water is becoming hugely problematic to the world.

Not only are groundwater resources depleting at an unprecedented rate, manmade dams cause such disturbance to the pattern of the ecosystem, that they are becoming unsustainable.

Coupled with the process of cleaning and purifying this water, the whole industry is highly pollutive and energy intensive. While moves are being made to desalinate seawater using solar power, this seems somewhat drastic when we aren’t efficiently or effectively using the very resource that some of us are lucky to have.

On a more basic level, when we consider that the water that comes from our faucets is usually drinkable, it seems somewhat of a waste to use this precious resource to water our gardens — especially since plants are one of the greatest filterers of water.

Equally, rainwater is drinkable with a little cleaning and can help us to save money on our water bills, reduce our workloads, preserve this very scarce resource. Like using the sun’s solar energy on our sites, cycling water through the site is a great way to create a more automatic self-running system.

Rainwater harvesting is an umbrella term that covers a myriad of techniques used to capture rainwater and spread it throughout the site, utilizing it for drinking, cooking, washing, watering the plants, and in some cases creating hydro-energy. While many people are familiar with rainwater tanks, harvesting methods are far more diverse than this, making rainwater a multi-functional element in the intelligent permaculture design of your site.

Brad Lancaster’s 8 Rules of Rainwater Harvesting

While harvesting rainwater can be served by a whole host of techniques, there are certain principles to follow that help you to understand which technique is most relevant, where to start, and how to progress through the site to create an efficiently networked system of rainwater harvesting methods.

That way you can implement a variety of earthworks or rainwater elements that allow this one function (capturing rainwater) to be served by several interconnected elements that work together to create a resilient network.

Who is Brad Lancaster?

Permaculture teacher, designer, and consultant, Brad Lancaster is a rainwater and water management specialist. He co-founded Desert Harvesters, a non-profit to help with water management for land regeneration.

Most famously, Lancaster wrote the revered guidebook to rainwater harvesting. A 3-volume series, Rainwater Harvesting for the Drylands and Beyond uses Lancaster’s 1/8th of an acre property to help demonstrate what rainwater harvesting is, how it can be used, and an array of best practices.

Volume 1 looks closely at why we should manage water on our sites, with a brief overview of strategies and assessment techniques. The second volume delves into the strategies in a more in-depth manner, focusing on earthworks (building with the earth), and the third book looks at cistern systems and tanks.

His series is undoubtedly the most comprehensive look at rainwater harvesting techniques and sets the precedent for sustainable water collection and usage. It is perhaps one of the greatest resources to get you started with rainwater harvesting.

The 8 Principles of Rainwater Harvesting

1. Begin with Long and Thoughtful Observation

As with all permaculture endeavors, observation is key to understanding what is happening on your site and how to improve it. Take a look at the water flow using all your senses. Run outside when it rains and follow the water to see the paths it takes, where it collects, and where is runs away too quickly.

Find out areas where it erodes the land or causes quagmires that may increase mosquito populations. Identify areas where the water infiltrates the land and where impervious surfaces cause it run away. Figure out what works and what doesn’t. This is your starting point.

2. Start at the Top and Work Down

The idea of the second principle is to begin at the top of your watershed and work your way down. You are looking for the highest point on the property. This can usually be done by looking at contour maps of your own site; if not you may have to walk the site and find the spots where the water runs away. By starting at the top, you have less volume and speed to work with. If you start at the bottom, you’re trying to work with all the water collected on its way down and this is far harder.

3. Start Small and Simple

We are often inclined to design with grandiose ideas in mind. Working on the ‘human-scale’ (what can be done by one person by hand) enables you to think of smaller solutions that can help to deal with your watershed from the get go.

Lancaster makes an important point that ‘One thousand small strategies are far more effective than one big one when you are trying to infiltrate water into the soil.’ This is because 1000 smaller strategies are easier to manage and do yourself, while also creating resilience through diversity. It also means that as you change the land, you can recognize the effect of these changes quite quickly. One big strategy that’s wrong could monumentally wreak havoc with your landscape.

4. Spread and Infiltrate

When water is left to run-off the land, it will find the path of least resistance. It will travel down every slop in all directions to form channels of water through the site. Like streams and rivers, these channels will carve the way into the land, causing scars and eroding the soil as it goes.

The velocity with which is travels off the site means it doesn’t have time to sink into the soil. The idea of rainwater harvesting is to encourage the water to infiltrate the soil in as many places as possible on the site. This enables your plants to have a constant water resource to draw from. In this sense, we want to divert the water around the site, spreading its usefulness, while also creating means for it to be absorbed.

5. Always Plan for Overflow

While we can calculate the amount of water that each element can deal with, there may be a time that it rains far more heavily than you planned for. These extra-heavy rains could cause beds to wash away as well as leading to soil erosion and a loss of resources. In this sense, every rainwater harvesting element that you design should plan for where the water will go if it overflows.

6. Maximize Living, Organic Groundcover

Groundcover refers to small, generally shallow-rooted plants that are low to the ground while covering the soil. Many gardeners tend to use clovers as groundcovers as their high nitrogen content will improve the soil. These groundcover plants will also hold water in the soil and prevent erosive run-off by creating a living sponge.

7.  Stack Functions to Maximize Beneficial Relationships and Efficiency

Like all elements in a permaculture system, rainwater harvesting elements should be multi-functional to ensure that efficiency is created through beneficial relationships. For example, berms (explained below) can serve as pathways around the garden, while groundcover crops can be edible and increase nitrogen in the soil, while also insulating the ground. Ponds can be turned into aquaculture systems and bio-swimming pools, while infiltration basins can provide extra beds to plant food and medicine.

8. Continually Reassess the Feedback Loops

It is important that we do not just implement a technique and walk away. In order to develop a complex and self-perpetuating system, we need to monitor how they affect the environment to discover both positive and negative feedback. In doing this, we can either change or adapt what we have created, while also being able to define the next clear steps to improve the system.

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