There’s a cheap, abundant resource that could help consumers save money and fight climate change: rainwater.
by Zachary Rybarczyk
Residents in eight cities around the U.S. could collectively trim up to $90 million a year off their water bills with simple rainwater collection techniques, according to a new report.
Urban rooftop rainwater collection, often overlooked or discouraged by complicated regulations in major cities and neighborhoods, could help individuals and families save money while improving water quality, says the Natural Resources Defense Council in a new report.
“Even under conservative assumptions, the study demonstrates that each city modeled can capture hundreds of millions to billions of gallons of rainwater each year, equivalent to the total annual water use of tens to hundreds of thousands of residents.”
And the yearly savings could be far greater for Americans than $90 million. The eight cities profiled in the NRDC analysis are only a snapshot of the different regions around the country.
Over 44 billion gallons of freshwater are used by public water suppliers on a daily basis in the United States, with consumers representing one of the highest individual daily usage rates in the world (between 100 and 165 gallons). As climate change and population growth drain some regional water supplies, urban dwellers may be vulnerable to water shortages or price spikes.
Much of the heavily treated, energy-intensive and perfectly drinkable water is wasted on tasks that could be used for non-potable supplies. For example, more than 11 percent of residential and 25 percent of commercial drinking water is spent on flushing toilets — over 2 trillion gallons a year.
NRDC has found that non-potable residential and commercial rooftop rainwater collection, which has been utilized in some regions of the US for some time to supplement residential outdoor activities, could be expanded to supply large cities with between 21 to 75 percent of their yearly water use.
The report lists four major benefits of capturing urban rainfall:
- Inexpensive, on-site supply of water that can be used for outdoor non-potable uses with little, if any, treatment, or for a variety of additional uses including potable supply with appropriately higher levels of treatment
- Reduced (or no) energy and economic costs associated with treating and delivering potable water to end users because capture systems often use low-volume, non-pressurized, gravity fed systems or require only the use of a low power pump for supply
- Reduced strain on existing water supply sources
- Reduced runoff that would otherwise contribute to storm water flows, a leading cause of surface water pollution and urban flooding
Lightly or non-treated, non-potable water, collected in rainwater basins, has the potential to replace nearly 80 percent of daily residential water usage (clothes washing, toilet flushing, and outdoor uses) that does not require drinking water.
Rooftop containment also has the potential improve water quality around metropolitan areas by preventing excess storm water (often filled with sewage, toxins, and chemicals that coat our sidewalks and streets) from washing into rivers, streams, and beaches. In fact, the EPA views urban runoff as “one of the greatest threats to water quality in the country,” and one of the leading causes of surface water pollution.
Unfortunately, rainwater collection is often hampered by overlapping and contradictory local regulations for non-potable indoor water use, which makes rainwater containment “overly complicated.” By addressing some of the simple rules than govern water use, rainwater collection could be a major factor in our ability to mitigate and adapt to climate change.
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While I generally approve of any effort to provide alternatives for urban water use, the idea that this would save huge amounts of money is laughably naive. Taking my own community (more suburban than urban) as an example, there is a simple relationship between the cost of water delivery, the amount of water used and the rate at which the costs are recovered. Use less water and the cost per unit increases, generally creating a political backlash for current office holders.
There are ways of preventing this, but it involves both local community and regional participation in setting goals. This is particularly true in California where urban users have the population (votes) and industrial scale ag has the ability to spin information like a perpetual motion top.
The latest version of this is playing out even as I make this comment with HR 1837 being “marked up” by the House Committee on Natural Resources this AM. The result of this would be to “privatize” a common resource.
So… your community has an unlimited supply of potable water that doesn’t cost anything to treat or to transport? Your community water supply has only fixed infrastructure costs?
Your sewer system similarly has no cost to treat or transport waste water?
Please do tell me where you live?
It sounds like you live at the bottom of a glacier (rapidly melting these days) and can just dump sewage into the river without treatment.
Thinking about the equivalent cost of the energy it takes to get that water “up there” in the first place and the potential of yet-to-be-determined whole systems “blue-sky” ideas, that $90 million savings may ultimately prove to be a very low number.
I have had a water harvester for 4 years, I use it for my greenhouse. The key is storage, the bigger the cistern the better.
One of the best guys on this subject is Brad Landcaster .
Pictures of my cistern :
http://water-diverter-harvester.blogspot.com/
I have worked on ferrocement tanks with applications for rainwater collection. The economics for rural countries that need water yet experience sufficient rainfall is very good … Two self-filling ten thousand gallon tanks with one reserved for emergencies makes quite a nice profit for a community and also provides opportunity for practicing democracy.
Similar techniques are applicable for the $5 per square foot house that pays for itself with reduced maintenance and insurance, and the flycatcher compost toilet.
http://www.ferrocement.com for complete info gratis or field manuals for schools etc.
I seem to recall a court case out West that basically said that rainwater harvesting was illegal, since the use of harvested (and held) water violated existing water rights held by others.
Does anyone else remember this (or something like this)? Or is my brain failing me?
The State of Colorado water law.
Rainwater collection is great and I’d love to do it, but it violates Colorado law. The water is considered owned by someone downstream.
To understand how critically important rainwater collection can be, a person only needs to live in a place where other sources of fresh water are virtually non-existent – an island! The island where I have lived for over 12 years is St. John in the US Virgin Islands. It is a volcanically formed island which has extremely little ground water with reverse osmosis plants producing very expensive potable water from sea water.
That expensive RO water is only directly available via water main distribution systems in the larger communities at over $20/1000gal. And if you live “in country” where about half the population lives, the cost to have that RO water trucked in is about $90/1000gal.
However we do have an average of 44 inches of rain per year (not that different from many mainland cities). Hence the Virgin Islands building code requires that buildings have rainwater collection systems that are proportional to the buildings’ sizes. This allows us to collect virtually free fresh water, thanks to nature’s water cycle distilling sea water through evaporation and then condensation in the form of rain.
For the 12 years here we have never had to truck in water and for the last 5 years I used my sanitary engineering background to set up and use a simple, yet safe potable water system that yields great tasting water from our cisterns. While I consider cisterns and nature part of our potable water system, the final filtering and purifying parts of the system cost less than $50 initially and less than $5/month to operate. It pains me greatly when I enjoy inexpensive fresh water while over a billion on earth do not.
Cities are coming to realize the need for rooftop rainwater collection including, where I used to live, Tucson, now actively pursuing this idea in light of ever-increasing water scarcity with the threat of desertification and in spite of their billion dollar Central Arizona Project aqueduct system put in late in the 1900’s. Cities as big as New York and Chicago are having to address various water related challenges and who knows what the effects of climate change will bring.
Shouldn’t rainwater harvesting receive serious consideration and implementation to head off future challenges while we have the chance to act?
JL -
Many thanks for your comments. As they point out , this ain’t rocket science, just good design.
Let’s look the cost of implementation.
For instance a home with four bathrooms. We will:
Install a gutter system & cistern with pump.
perform maintenance.
individually replumb each toilet.
have a makeup system to add water when cistern is low.
So, annually I pay the city $400 for water in & out, save 25%, so save $100. What’s total cost of project? At a minimum $3000, so payback is 30 years? or more likely 50 years.
Project is doable only if you live in a rural area without city water.
Well, while you did not indicate where you live, just wait until the water in your area becomes scarce or the water rates go through the roof – then see where your ROI figures go.
Using annual average water-use statistic for household use in Denver in 1999 [1], we get a figure of 127,400 gallons/house/year.
Using the total costs for Denver, CO from the graph in the article ($3.86/1000 gal/year), we get an annual cost of $491.76. Let’s ball-park it to $500/yr. Would mean that your ROI on a $3000 install (assuming only 25% savings of utility costs) would be 24 years.
HOWEVER, if you use the same amount and live in Ft. Myers, FL ($13.51/1000 gal/year), you’d be spending $1,721.17, let’s ballpark it to $1600. Your ROI would then be 7.5 years.
And this all assumes that the price of water doesn’t rise nor that the price for doing such retrofits doesn’t fall (it is, after all, about economies of scale). Or that other fees don’t come into play.
[1]:http://www.drinktap.org/consumerdnn/Home/WaterInformation/Conservation/WaterUseStatistics/tabid/85/Default.aspx
Good concept, but very misleading math! The fixed costs do not go away when you reduce usage and water systems are very capital intensive. Reduced consumption will require rate increases in the short run. Short-run savings will be limited to savings in variable costs (water, energy, chemicals). In the long run, capital costs can be avoided too, if changes in demand are reflected in capital planning. But not all costs are avoidable as long as we want to maintain infrastructure not just for drinking water, but for wastewater and fire protection.
With all due respects, Jan, while the fixed costs of the existing infastructure do indeed remain the same, the variable costs go down due to the decreasing need to supply the water that has been augmented by rainwater collected and used and a decreased need in future capital improvements to the system.
There are people in the Abacos that have been using cisterns for years. They carve the tanks out of the coral & build ther homes over them. They keep a few fish in them to keep it “fresh” & it works. Collecting water & zeriscape, brown water irrigation are great ideas. Thanks for the excellent, thought provoking, article.
The main reason why we got a rainwater tank is not cost savings. Our water rates bill shows most of the cost as infrastructure. We could cut out water altogether and still only save about $100/year.
All the same, you can pick up a tank fairly cheaply and hook it up for not a great cost, depending on how far you want to go.
The reason for us having a tank is so that we have water during droughts when water restrictions are imposed, particularly for our garden fruit and veges. During a drought we are also conscious of wanting to save as much water as possible so that people living downstream don’t run out of drinking water too soon.
We know we will probably be looking at more and longer droughts this century.
If towns don’t manage home water tanks properly you can end up with all sorts of contaminants entering the town supply from badly installed tanks (leaking contaminated water back into the system).
Water tanks are great, but they are not the answer to everything. And there is no way they cost less than town water. The efficiencies of scale in a good town water supply make it much more cost effective. I’d suggest localities that need to save water locally could look at things like catching and saving storm water.
I might add that what I am observing now, with my background in sanitary engineering in municipal water treatment practices,that with everything coming down stream or out of the ground, including a wide variety of toxic chemicals dumped upstream (or pumped underground in disposal wells)and now including discarded pharmaceutical drugs that have been flushed down the toilet or lawn and agricultural herbicides and pesticides that have run off with storm water into the upstream tributaries feeding downstream municipalities’ drinking water systems that were never meant to and have no ability to treat this myriad of a “chemical cocktail.” While there are contaminates that can come down from the air with rain water – Thank you, I’ll accept that risk.
It cost me about $150 for 2 x 255 gallon and 2 x 30 gallon water containers, and a few connecting parts. Other ideas for landscaping use are french drains and rain gardens to keep water on your property so that it will require less water in times of drought. Here, water running off properties floods the streets and runs into the Gulf of Mexico, taking street and storm-sewer contaminants with it. It is not reasonable to assess the costs so high, and the local government could subsidize the cost, for example by obtaining large lots of containers and selling them at a reduced rate.
I meant also to say that we are in an extreme (and was exceptional) drought here, yet street flooding is so bad that Houston was told to stay home a couple times recently. All the flooding is caused by run-off.
Something is not right.
If you look at the Table 5 cost analysis, most of the savings occurs from saving on wastewater flow.
Think about it. If you use rainwater for your toilet, do you save on wastewater discharge?
If utilities such as sewers receive less revenue from water use (because rainwater reduces meter charges), where do you think the sewer utility is going to make up the lost revenues? The wastewater flow doesn’t change. You guessed it, they will increase the wastewater rate to all users.
Does anyone else see this?