Archive for July, 2009

If the Drought is Over, Why Worry About Rainwater Collection?

July 18, 2009

The drought may or may not be over, but Georgia’s water supply challenges continue. You may have read about the ruling of federal court judge Magnuson which states that the Atlanta must stop using Lake Lanier water within 3 years and that congress will need to get involved with any agreements. You may be aware that plans are being made to double Atlanta’s water supply using a combination of new reservoirs. With the new ruling, efforts in this areas will no doubt be stepped up. I have been wondering if rainwater collection could help avoid at least part of this enormous expense and the impact it will have on the area. I certainly do not have all the answers want to raise some of my questions to see what the opportunities might be. I encourage comments and questions to to pose your questions, comments, and debate.

To start this analysis I Iooked as an extreme case at what would happen if each and every home in Atlanta had rainwater collection and used it for all non-potable uses both indoor and outdoor. In round terms I understand there are about 140,000 single family homes in Atlanta. Daily water usage is conservatively around 85 million gallons per day (it’s actually a bit higher) according to the City of Atlanta . Let’s go back to our typical family of four. If this family were to install rainwater collection for all non-potable uses water usage savings could be up to around 100,000 gallons annually (50,000 indoors and 50,000 outdoors). If all homes saved 60,000 gallons per year using rainwater collection and other measures, this would amount to 8.4 billion gallons saved annually if they all had rainwater collection systems which equates to 27% of City of Atlanta’s water use. Pretty impressive.

Now, we all know that not all homes will install a rainwater system, at least not in the short term and we also know that the typical family of four I keep referring to may not be typical for Atlanta, but this analysis does show that the impact of rainwater collection is potentially large. The next point to ponder is cost. What would it cost to install rainwater collection systems all across metro Atlanta and how does that stack up to the expected capital outlay to meet the proposed reservoir expansions. According to a recent AJC article, the current water plan will require $4 billion in spending between now and 2020. Outfitting all single family homes with rainwater collection system would cost $1.4 billion assuming $10,000 per system (in many cases the cost of rainwater collection is a lot less; I wanted to be really conservative). These rough numbers indicate that it may actually be a worthwhile investment for the city to pay people to install rainwater collection system in their homes than to build what amounts to huge rainwater storage tanks in the form of new reservoirs.
I do not propose that the city fork over thousands of dollars to home owners to build rainwater collection systems. But, I would advocate some sort of loan program to incentivize people to do so. In fact, the EPA already has a program for state and local governments to use for clean water projects. I am told by contacts in the water conservation industry that this program does apply to things like rainwater collection systems for homes. In their website the EPA indicates that loans can be for up to 20 years and average a 2.2% interest rate. A program taking advantage of this could be very interesting for both home owners and the city. For home owners, this sort of financing would virtually assure that the payments on the loans would be less than the monthly water bill savings, making the project cash flow positive from the very beginning. For the City of Atlanta, the benefit could be reducing the need for large capital outlays to build increased water supply among other things.
This sort of idea is not without precedent. The City of Berkley, CA did something similar to incentivize home owners to invest in photovoltaic solar systems through a loan program. This was done to help avoid investment in a new power plant and to help with green house gas generation.

Other measures may also need to be considered in the face of the Lake Lanier spigot being turned off. It may be necessary to impose a permanent and actually enforced outdoor watering ban and require that all new construction has rainwater collection and other water saving features. Such measures have been implemented in other regions with water challenges such as Australia and New Mexico.