By Haley Paul on Feb 21, 2011

A Budgeter's Guide to Rainwater Harvesting

By implementing passive rainwater harvesting techniques such as swales and berms, these native plants could be accessing supplemental rainwater that would cut back on the plants’ potable water use. Photo: Haley Paul, Earth911

With much of the U.S. digging itself out from piles of snow, those toasty July days seem an eternity away. But the warm, dry months will come, and there is no time like the present to start planning a rainwater harvesting system to help offset your skyrocketing water bill once the hot summer months arrive.

Where to use harvested rainwater

Because the bulk of residential water use comes from outdoor uses such as irrigating landscapes, the simplest and most cost-effective way to use captured rainwater is for outdoor purposes.

In her publication Harvesting Rainwater for Landscape Use, author Patricia Waterfall explains, “Harvesting rainwater can reduce the use of drinking water for landscape irrigation” and “when coupled with the use of native […] plants, […] is an effective water conservation tool.”

Do you qualify?

If you pay for water to irrigate any portion of your outdoor landscape, including vegetable gardens, rainwater harvesting is for you. Since most yards require some supplemental watering to look good, offsetting a portion of that water with free rainfall saves on two fronts: water and money.

To choose a system that works for you, it is important to consider existing infrastructure (the roof and the yard) and regional climate (how much rain falls in your area). An ideal rainwater harvesting system does not capture more water than a landscape can use because water surpluses can become a nuisance if water is not utilized within three to four months (think stagnant water).

Choosing a method

There are two main methods of rainwater harvesting: active and passive.

According to the Tucson Botanical Gardens, active systems integrate a storage container into the system to catch rainwater runoff for later use on the property.

Passive systems, on the other hand, “use earthworks to control surface water flow and use the soil as the storage container. The passive system requires planning and observation of the natural water movement on the land but requires no gutters or storage containers.”

Keep in mind that using one form of collection does not negate the other; passive and active methods of rainwater harvesting are often used in tandem to utilize the most rainwater possible.

How to harvest (when you’re on a budget)

There are numerous ways to divert rainfall from its journey to the storm drain and instead put it to use on your property.  By starting with the basic and inexpensive options, you can get a better feel for what your yard needs, making it easier to advance your rainwater harvesting system in the future (should you want to).

Simple active harvesting option

Barrels collect rainwater from the gutters of the house. A hose is connected to the barrels, which waters nearby landscape plants. Photo: Patricia Waterfall, University of Arizona Cooperative Extension.

If you have a roof and gutters, you’ve already accomplished a major step towards rainwater harvesting. Houses with gutters generally divert the rainwater falling on the roof to one main location. Place a large barrel or a 55-gallon drum underneath the main downspout to capture and store rainwater.

Make sure the container you choose has an external pipe and a valve so you can connect a hose to water your plants as well as shut off the water coming from the barrel. Also, remember to keep your gutters free of twigs and leaves so the gutters can continue to direct the flow of water to the downspout.

Lastly, make the system even more efficient by placing the rainwater collection container on a raised platform so as to receive the added benefit of gravity. By elevating the barrel, gravity helps maintain the pressure in the hose so you can irrigate plants further from the collection and storage point.

Simple passive harvesting option

In this illustration, rainwater is harvested from the roof and directed into a furrow that flows to a holding area where water percolates into the soil, watering the plants. Photo: Patricia Waterfall, University of Arizona Cooperative

To implement a simple passive harvesting system, get ready to bust out the shovel. In a simple system, rainwater is put to immediate use and consists of a catchment area (the roof) and a means of distribution (gravity).

Rainwater flows from the roof but instead of collecting in barrels via gutters, rainwater falls from the roof into a dug swale. The swale then channels the rainwater towards a holding area where the landscape plants or the vegetable garden utilize the diverted water.

An added benefit of passive systems is erosion control. By keeping more water on-site, less water and soil flush out into the street during storm events.

Things to keep in mind

If using an active rainwater harvesting system that includes large barrels or other storage containers, size limits and location restrictions may apply. Check with your local city ordinances to see if there are any restrictions on the books for rainwater harvesting.

To learn about more rainwater harvesting, including more advanced options, check out the website for Brad Lancaster, author of multiple rainwater harvesting books or the Online Rainwater Harvesting Community.

You may also like:
Help Solve the Water Crisis
Green and Blue Coming to a Rooftop Near You
Colorado Bill Legalizes Rainwater Harvesting

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Comments

  1. Gregg Goodrum says

    Haley,
    I was wondering about something that I seldom hear addressed when talking about harvesting rainwater. I live in the Florida Keys and we are under a state mandate to meet nearshore clean water standards by the year 2015. Most areas have chosen to sewer and as a result, our sewer bills will be tied to our water consumption. I would like to hear a discussion, or read about systems that could retro-fit a house’s toilets to make use of harvested rainwater instead of city water, thereby reducing our use of city water and running up huge bills. Any additional water collected, of course would be used for landscapes, car washes etc.

  2. Dennis says

    Haley,
    We are a start up biofuel feedstock co.
    located here in mesa, az. We are using
    a source for fuel pellets that has yet to
    be exploited. Need to gain certification
    like FSC, or etc. could you please
    forward me contact info. so I could
    discuss some of the things we are
    working on and draw on your expertise.
    Thanks Dennis

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