Archive for March, 2010

Collected Rainwater – The Way to Keep Atlanta Green

March 15, 2010

By Robert Drew

Visitors to Atlanta are amazed by the beauty of our lawns and gardens.  We all enjoy the greenery and vibrant colors of our little piece of paradise.  But, with the specter of losing access to Lake Lanier water, the threat of more droughts like those of 2006-2008, and the 50% projected increase in fresh water consumption over the next 25 years, how can we assure Atlanta will stay as green and beautiful as today?  A big part of the solution can be rainwater collection.  Using collected rainwater can eliminate the need for municipal water supplies for outdoor watering and just makes financial sense for those of us who do it.

So, how can you rely solely on collected rainwater for all your outdoor watering needs while maintaining your lawn and garden at its optimal best?  No, this does not require planting cactus and converting your lawn to a rock garden.  In fact, you can keep planting those gorgeous annuals and by all means you can have the most bountiful vegetable garden in the neighborhood.

First, we’ll assume you have your automatic sprinkler system well maintained with no leaks.  Ideally, it uses a moisture sensor and high efficient heads with drip irrigation wherever possible.  Next, you’ll ideally keep turf areas balanced and fertilized with one of the natural fertilization programs that now exist.  Check out Earth Balance Organics for a great way to get turf roots to grow deep to make even fescue more drought resistant.

Ok, so with that basis let take a look at rainwater collection which keeps the rain that falls on your roof and hard surface for future use.  Now, if you have a tiny roof top and acres of fescue, you may be out of luck.  But let take a more normal situation with a roof top of 3,000 square feet with a typical 3,400 gallon cistern which is irrigating around 4,000 square feet lawn and garden.  There’s a vegetable garden and plenty of annuals around for accent and a well designed accompaniment of bushes and perennials.

How well can we water this lawn and garden solely on collected rainwater in a normal rainfall year?  Taking 2005 as the last year that was close to the 30 average, let’s look at day by day rainfall to see if plants get all the water they need which is around an inch of rain a week with one deep watering.  In this case, there was plenty of rainwater collected from March through mid-September for all needs.  Yes, the tank was empty a few times but never longer than a few days.  Turf experts will tell you that even thirsty fescue stays healthy for a week without watering provided it’s well fertilized and has a good root structure.

Pretty impressive right?  But you probably wonder how the same system performed in 2007’s record drought.  First of all, there would be no watering ban with the rainwater collection system.  With that in mind, it’s clear that having rainwater collection would be far superior to no watering at all.  Even though the tank ran dry more often than normal, we still received enough rain during the drought (an average of 2.4” a month during that summer) to replenish the tank in order to keep plants alive.

The best news is that a rainwater collection system is a sound investment and typically has a very positive return on investment with Atlanta’s sky high and climbing water rates.  In most cases, rainwater collection costs less than drilling a well, does not have a risk of a dry well, and does not deplete ground water.  In fact rainwater collection helps replenish groundwater supplies while preventing storm water runoff.

You could even take things a step further to use filtered water from your showers and laundry (gray water) for drip irrigation.  Using native Georgia plants helps reduce water demand and can be very economical if you choose to do plant rescues with the Georgia Native Plant Society.  Switching turf areas to drought tolerant species like Bermuda grass and some types of Zoysia is really catching on.

In any case, rainwater collection is central to being able to create beautiful lawns and garden.   In fact, it may be the only truly sustainable way to keep Atlanta green.


Many of us learned with the outdoor watering ban during the drought of 2006 to 2008 that plants can thrive on a lot less water than we had previously given them.

How long can you wait between watering before the lawn starts to go brown?

Watering guidelines for different grass types in sunny areas:

12 – 21 days: Bermuda grass, St. Augustine grass, Centipede grass

8 – 12 days: Fine fescue, Tall fescue, Zoysia

5 – 7 days: Ryegrass, Kentucky Bluegrass, Bentgrass