Rainwater harvesting is collecting the run-off from a structure or other impervious surface in order to store it for later use. Traditionally, this involves harvesting the rain from a roof. The rain will collect in gutters that channel the water into downspouts and then into some sort of storage vessel. Rainwater collection systems can be as simple as collecting rain in a rain barrel or as elaborate as harvesting rainwater into large cisterns to supply your entire household demand.
The idea of rainwater harvesting usually conjures up images of an old farm cistern or thoughts of developing countries. The reality is that rainwater harvesting is becoming a viable alternative for supplying our households and businesses with water. It’s not just for the farm anymore! There are many countries such as Germany and Australia where rainwater harvesting is a norm. Due to the green building movement, you will be seeing rainwater harvesting systems become more popular here in America.
The collection of rainwater is known by many names throughout the world. It ranges from rainwater collection to rainwater harvesting to rainwater catchment. In addition, terms such as roofwater collection or rooftop water collection is also used in other countries.
We believe that rainwater harvesting is a viable technology in an urban setting. All that is necessary to take advantage of this resource is to capture the free water falling on your roof and direct it to a rainwater storage tank. By doing this, you can take control of your water supply and replace all or at least a substantial portion of your water needs. Rainwater harvesting systems can be configured to supply your whole house and/or your landscape needs.
Rainwater harvesting is important for several reasons but one of the biggest is the fact that we are tapping out water conservation gains inside our homes so we need to start looking outdoors for more opportunities.
The following graph shows the gains that have been achieved with our indoor water fixtures through the combination of governmental standards and innovation by fixture companies. As you can see, we don’t have much more room to go in terms of achieving more efficiency gains with our indoor fixtures. What’s next… the 0.2 gallon per flush toilet? Probably not!
This phenomenom is known as the law of diminishing returns. So where will the next revolution in water conservation take place? We believe we offer services in the areas where this revolution will take place.
You can essentially use rainwater anywhere you use tap water. The idea of using drinking water to flush our toilets and water our lawns is wasteful and irresponsible, especially in light of population growth and water shortages across the country. Rainwater collection is a technique to green your home and to lessen your environmental footprint.
There are basically three areas where rainwater can be used:
Here are some ideas for specific uses of rainwater:
The amount of rainfall that you can collect is governed by the following formula:
1″ of rain x 1 sq. ft. = 0.623 gallons
To calculate the amount of rainwater you can collect, you need to know your annual average precipitation for your area. You can use the precipitation map below to find an approximate amount for your area.
Alternatively, you can find an exact precipitation amount by looking at the NCDC Monthly Precipitation Probabilities and Quintiles.
Find the closest weather station to you and use the 0.5 row to determine your annual average precipitation.
Once you have the annual average rainfall in your area and the square footage of your collection surface, you can plug these values into our rainwater collection calculator.
So you’re convinced that you want to start collecting rainwater at your house. Below you will find the resources to educate yourself on the best method for harvesting rainwater in your situation. You will also find information about the basic components of a rainwater collection system. Even though rainwater catchment is an old technology, there have been many improvements over time through product innovations.
The only thing that differs in the following methods is the scale of the system. They all follow the same principles but differ on aesthetics and actual water conservation effectiveness. Click the pictures for a closer look.
This method is the most common and one that many people are familiar with. This involves installing a barrel at a gutter downspout to collect rainwater. The actual barrel may be a recycled barrel or a new commercially available rain barrel.
This method is a variation of a rain barrel set-up, but it involves a larger storage volume. Essentially, the collection pipe “drys” after each rain event since it empties directly into the top of the tank.
This method involves locating the collection pipes underground in order to connect multiple downspouts from different gutters. The rainwater will fill the underground piping and the water will rise in the vertical pipes until it spills into the tank. The downspouts and underground collection piping must have water-tight connections. The elevation of the tank inlet must be below the lowest gutter on the house.
The image below shows a complete rainwater collection system. While some of the components shown are absolutely necessary, not all of the components listed are required. Although, all of these components will help create a harvesting system that is highly functional and nearly maintenance-free.