Irrigate Your Garden and Lawn with a Rainwater Harvesting System

So, you are interested in building a rainwater harvesting system. Whether you live in an urban or rural area, this will help you to reduce your water bill and conserve water resources. A rainwater harvesting system is ideal in areas with lawn and garden watering restrictions. The following tips are based on my experience with Brad Lancaster's "Rainwater Harvesting for Drylands". I highly recommend these books if you are serious about building a system. These will help you to make the most of your time and effort during the rainy season!

Depending on the use to which you plan to put your freshly harvested rainwater, the type of system you build will vary. Before you dig any ditches or purchase any pipe, determine how you will utilize the water you capture. The two types of systems are earthworks and tank-based. Earthworks are used to capture run-off containing impurities such as dirt and chemicals. Water from the street gutter is a good example. These systems can also be used to collect greywater from your indoor sinks. As the name implies, earthworks involve altering the Earth's surface to channel water. Typical structures include berms and basins, terraces, French drains, and infiltration basins. Water follows the path you choose, and is typically stored underground in large mulch pits. The primary reason for selecting the earthworks approach is water quality. Dirty water should not be used for drinking or washing, and can be harmful to sensitive plants. Earthworks are excellent for watering trees, shrubs, and other landscaping. The second type of system, tank-based, is used to collect rainwater directly from roofs and surfaces, which can be coated with a special rain harvesting paint. This water is generally cleaner than ground run-off, and can be used for washing. The main use for tanks in irrigation is long-term storage of rainwater to be used during the dry season. A tank-based rainwater harvesting system is ideal for small yards and gardens. It is common to see combinations of earthworks and tank-based systems.

Once you have determined how you will utilize your rainwater, observe the flow of water on your land during rainstorms. It is important that you have a good understanding of the hydrology of your property, as this will help you to make your system more efficient. It will most likely take you more than one storm, or possibly an entire rain season to get the big picture. Observe all that happens during and after the storm. Where does the water flow naturally? Are there locations where the water forms puddles? Is the water polluted? Are plants more dense in certain areas? What are the soil conditions? These are a few questions to ask during your observations. Be sure to take notes and pictures to help you create your master plan.

Now that you know how you will be using the harvested rainwater, and know every last detail about the hydrology of your land, it is time to start construction. Always start at the highest points on your property. Water seeks to move downhill. By collecting at the high spots of your land, you gain a key ally in your quest, water pressure. Gravity will then aid you as you distribute the water across your yard and/or garden. This step is important regardless of the type of system you choose. Build your system in small and simple components. It is essential to keep your system as simple as possible, because you will be doing all of the maintenance and repair. This will also allow you to perfect each component before constructing the next section. Be sure to include an overflow route for all components of your system. Not all rainstorms are equal, and some can wreak havoc on your project. Additionally, heavy rains can give you extra water that can be stored in a tank or diverted to an underground mulch pit. As your system develops, look for ways to perform multiple functions with different components. For example, berms can be used as walking paths around a flower bed.

Rainwater harvesting is not just about capturing and transporting water. A major component of a good system is increased soil and organic matter water storage. Slow the water down to prevent erosion, spread it across your land, and sink it into the ground. Water should run slowly through your system so it can infiltrate into the soil. Increased soil moisture will help plants to flourish. In order to keep water in the soil and improve infiltration, grow a living sponge of plants and mulch. Plant covered areas soak up more water than bare dirt areas. Bare soil is easily compacted, which is not conducive to infiltration.

Finally, always seek to improve your system. Continue the observations you started making during the planning phase. Re-visit the questions you asked, and strive for improving efficiency. Be careful! Once you get started, you may never want to stop working on your masterpiece!