Wastewater Recycling: Creating Water So Pure We Can Drink It

Wastewater recycling, reclaimed water, and Indirect Potable Reuse (or IPR) are all ways of treating wastewater and reusing it rather than treating it and dumping it into the ocean.

San Diego reuses wastewater for irrigation, in its purple pipe system.  Purple pipe is so-named because it requires two sets of plumbing, one for drinking water (potable use) and a second (purple) set for reclaimed water for irrigation.  It’s easy enough to install when constructing a new building, but otherwise it’s a major retrofit, and either way it’s not cheap.  But during a bad drought in 1989, purple pipe was touted as the only way we would

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Photo Credit Lighthawk / Matthew Meier Photography

make it through with enough potable water for showers and drinking.  The City Council even passed an aggressive ordinance to force anyone who could reasonably use reclaimed water for irrigation or industrial uses to do so.  But the drought ended, and since then the ordinance has been largely forgotten and essentially unenforced.  In fact, according to a Sign On San Diego article, San Diego only uses 15 percent of its two reclaimed water plants’ capacity.

 

Now, the city is taking another look at wastewater recycling for drinking water.  (Check out how purple pipe and IPR compare – spoiler, IPR wins.)  Mayor Jerry Sanders supports a new demonstration project to test the safety of IPR for drinking water – a definite improvement on his previous stance of ceremonially vetoing the “toilet to tap” project.  The latest test builds on the successful use of wastewater recycling in:

  • Singapore, where they use reservoir augmentation, the very same process proposed for San Diego, and bottle and sell the stuff under the brand name NEWater

  • And closer to home, Orange County, where they use wastewater recycling for groundwater replenishment

The demonstration project will last a year and is required by the California Department of Public Health to prove the project adequately protects the public health.  Tours of the facility are open to the public so you can see the high level of treatment the water receives.

The Advanced Water Purification process, which consists of microfiltration, reverse osmosis, and treatment with hydrogen peroxide and ultraviolet light, actually removes more contaminants from the water supply than do the processes used to clean raw imported water.  IPR water has been found to contain lower levels of all but six of the 232 tested pollutants, and those six were all still below levels that cause health concerns (check out page 108 of this report for details). The tested pollutants include pharmaceuticals and endocrine disrupters, which are a common concern about IPR water.

In the words of Ronald Coss, the technical manager of the Water Reuse Study that made the above finding, “the human health risk from consuming [IPR water] directly is negligible, especially when compared to current drinking water standards and with other water supplies available to San Diego.  Augmenting San Diego’s raw water supply with [IPR water] would result in an improvement to water quality over current water supplies.” 

San Diego Showdown: IPR vs. Purple Pipes

This is the fourth of a 5-part blog series examining the nature of our local water supply and how to increase the reliability of our supplies now and into the future.

Today’s match-up features two contenders, both aimed at solving San Diego’s water crisis.  

In the first corner, the “purple pipe system” is looking to continue its reign in San Diego.  San Diego currently reuses a small fraction of its sewage for irrigation.  This recycled water is distributed through a separate purple pipe system.  Because the water is non-potable, it is not fit for human consumption.

In the second corner, the up-and-coming “Indirect Potable Reuse” (IPR) is looking to solve San Diego’s water problems.  In scientific terms, IPR is a process to treat wastewater and sewage using advanced technology to produce potable water fit for human consumption.  Essentially, we would be drinking purified sewage.  Right now, you are probably cringing at the thought of drinking recycled wastewater; I know I did.  But then I did some research, and I found out that the water produced from IPR is actually superior to our existing water supply.  How is this possible? 

First, advanced water technology removes any remaining solids through microfiltration.  Next, reverse osmosis is used to eliminate viruses, bacteria, pharmaceuticals, and other microbes.  The water is then disinfected by UV light and hydrogen peroxide.  Finally, it is added to groundwater or surface water reservoirs where it is further purified by natural processes.  Once drawn from the groundwater or reservoir, the recycled water goes through the standard water purification process all drinking water undergoes to meet EPA standards.  Once this IPR-produced water is fit for consumption, it is distributed through the existing drinking water infrastructure.  Now that doesn’t sound so bad, does it?

Round 1:  Costs

The cost of producing one acre-foot of water with IPR ranges from $1,200-$1,800.  The purple pipe system ranges from $1,600-$2,600 per acre-foot.  

Purple pipe recycled water cannot be added to the existing drinking water infrastructure, so it requires a separate pipe system which costs about $2 million per mile to build.  It also requires homes and businesses to be plumbed with two sets of pipes—one for recycled water and one for potable water.  This is beginning to sound expensive!  

Although the purification process of IPR sounds expensive, the City of San Diego estimates that implementing IPR would be cheaper than expanding the purple pipe system.  This is because IPR negates the need for a separate water infrastructure and would maximize the use of the available recycled water supply.  

IPR – 1; Purple Pipes – 0

Round 2:  Energy

The energy intensity of the IPR process is higher than that of the recycled water in purple pipes.  Compared to non-potable recycled water, IPR generates a higher carbon footprint.  However, IPR uses significantly less energy than other potential water sources in San Diego, such as desalination or imported water.

IPR – 1; Purple Pipes – 1

Round 3:  Environmental Impact

By using recycled wastewater, IPR reduces the amount of waste flowing to the Point Loma Treatment Plant.  In doing so, IPR reduces the amount of potentially harmful pollutants being released into the ocean from the Point Loma Plant’s effluent.    

Purple pipe recycled water does have some red flags.  Particularly, the use of non-potable recycled water can lead to the accumulation of byproducts over time in the irrigated soil.

IPR – 2; Purple Pipes – 1

Round 4:  Water Quality/Safety

Studies show that water produced through IPR treatment processes contains fewer contaminants than our existing treated imported water supply.  Further, a study performed by the National Research Council concluded that there were no significant health risks as a result of IPR.  
Because the water in the purple pipes is not treated to the point that it is drinkable, it contains pathogens and harmful chemicals. Simply stated, the consequences of ingesting non-potable recycled water can be severe.      

IPR – 3; Purple Pipes – 1

After four hard fought rounds, IPR has dominated the ring, proving that it would be a strong, viable addition to San Diego’s arsenal for fighting the water crisis.  

Still think “from toilet to tap” sounds less than appetizing, or has your mind changed?  Tell us what you think!  

Where does San Diego’s water come from?

If you have lived in San Diego for any length of time, you have probably noticed that it doesn’t rain very often here.  Yet if you look around, you’ll find you’re surrounded by lawns and swimming pools.  Where does the water come from to support all of this?  The short answer – not here.  San Diego County is a dry one, where a few isolated areas, the wettest in the county, get up to 45 inches of rain per year.  The driest gets nine.  San Diego city, where Coastkeeper is located, gets between nine and twelve inches per year.  Compare that to Northern California, where the wettest areas get up to 125 inches annually and where 40 to 75 inches is not uncommon. See this map for a breakdown of the annual rainfall in San Diego County, and this one for the average annual rainfall in California.  

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Image Credit San Diego County Water Authority, Sources of San Diego County’s Water Supply

San Diego’s limited amount of rainfall, in addition to other local sources, only accounts for about 20% of its water supply.  (Local supply includes surface water, or lakes and streams; groundwater; recycled water, also known as ‘purple pipe’; and conservation.)  The other 80% must be imported.

The Colorado River, source of half of San Diego County’s water, was first allocated in 1922 in the Colorado River Compact.  The Compact divides the usable flow of the Colorado River – 7.5 million acre-feet (an acre flooded a foot deep) – between the Upper Basin (Colorado, New Mexico, Utah, and Wyoming), and the Lower Basin (Arizona, California, and Nevada).  Each basin subsequently divided its portion among its member states, assigning each state a number of acre-feet for its entitlement.  This is important, because that assigned number for each state stays the same no matter how much water is actually in the river.  Problems have arisen since the original apportionment due to both simple squabbling over who should have the bigger slice of cake, and more problematically, because the cake isn’t actually as big as it was thought to be when it was apportioned.  The 7.5 million acre-foot “total” that can be taken without harm to the river was measured during a wet year, and so when the states use their allocated amount of water, they use more than the river can spare.

The State Water Project has its own set of problems as a water source.  The water ultimately comes from the Sacramento/San Joaquin River Delta.  The Delta is currently overdrawn, menacing the seven endangered and threatened fish species that call it home.  One in particular has served as the poster child for the recent Delta debates – the Delta smelt.  It’s a small fish, easily held in the palm of the hand, and its susceptibility to pollution makes it a good water quality indicator.  Concern for the species’ survival helped push through the Delta Plan, new legislation from November 2009 which puts conservation of the Delta on par with providing more reliable water supply to Southern California.  This has the effect of reducing the water transferred to Southern California – good for the fish, but inconvenient for the humans.

The humans have always had a bit of a problem with water supply in Southern California.  They have refused to recognize its limits, preferring instead to rely on massive water relocation projects to meet their needs.  This is not a sustainable path – there are very few other places we can take water from.  We need to start learning to conserve and live within our limits.   Visit http://www.bewaterwise.com/ for some ways to conserve.

Water Unwise: Answers to the burning questions

This is the third of a 5-part blog series examining the nature of our local water supply and how to increase the reliability of our supplies now and into the future.

Recently we posted a video of watering turf grass at Liberty Station. We asked you to see if you could spot whether there were any water unwise things in the video. I am sure you have been waiting with baited breath for the answer.

As I hinted in the last blog post, to get a sense of what is technically incorrect, we need a quick review of what our local ordinances say about irrigating.

  • First thing we need to know is that the San Diego City Council removed the Drought Level 2 status. Our City Council exercised some foresight last year and made a few of the drought level 2 restrictions permanent. Now, drought or no drought, there are just some things you cannot do, end of story.
  • Which brings us to the next important things you need to know – it is still illegal to water your lawn between 10 a.m. and 6 p.m. (June to October) and 10 a.m. and after 4 p.m. (November to May); and “City of San Diego water customers must prohibit excessive irrigation and must immediately correct leaks in their private water systems” (emphasis mine). The City’s regulations now state that customers “shall not allow water to leave their property due to drainage onto adjacent properties or public or private roadways or streets or gutters due to excessive irrigation and/or uncorrected leaks.”

Thus, according to the letter of the law, Liberty Station is within the bounds of legal limits in terms of when they water all that turf – the video was shot in May, at 9 AM. BUT, the video clearly shows excessive irrigation (as evidenced by the water flowing on the sidewalks, pooling around the sprinkler head and flowing into a drain).

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Jill Witkowski

The video demonstrates a clear violation of the letter of the law.

But beyond that, there is a clear violation of the spirit of the law as well, which in my mind is meant to keep all San Diegans – whether they manage a small house or a large commercial development – living within our water means. Given our climate and troubled water supply, we should always be striving to make the best water use decisions possible. To their credit, Liberty Station is participating in a pilot Water Savings Performance Program. They have installed an automated irrigation system that determines the length of time and the days to irrigate based on weather, soil, microclimate and plant material. This is a good start but is clearly not sufficient.

But what is a historical site that is trying to pay tribute to its military roots supposed to do?

Well, there are many things Liberty Station could have done and still could do. As Morgan, one of our commentators pointed out “Turf is not water wise … period.” There are other native and drought tolerant ground covers that look similar to turf grass and would help maintain the look of old military training fields of yore.

While it is great that Liberty Station has installed a fancy water-saving irrigation system, they lose half the battle if they don’t check to make sure it is working properly:

  • sprinkler heads spraying water onto concrete should be addressed immediately;
  • lawns could easily be watered earlier in the morning (just around dawn is generally considered best);
  • water should be applied more slowly by switching to more efficient irrigation heads (thanks again to our commentator Morgan for that idea).

Of course, these kinds of changes cannot happen overnight. But with a thoughtful plan for improving water management on site, Liberty Station could identify opportunities over the coming years to change its water path. We believe that any place – not just Liberty Station – can and should craft plans of action that lays out a vision and tasks for achieving water sustainability.

 


 

 

 

That’s Right: Get Over the Yuck Factor of Toilet-to-Tap

Saturday’s Union-Tribune ran an editorial rescinding its previous opposition to indirect potable reuse, a water supply option which would recycle treated wastewater into water so pure we could drink it. We’ve been advocating for this water supply option for many years and would like to congratulate the paper for stepping back from the brink to re-think San Diego’s water crisis.

What a difference two-and-a-half years make.

In September, 2008, this Editorial Board’s assessment of the pilot project to recycle wastewater at San Diego’s North City Water Reclamation Plan did not mince words, advising the City Council to ‘face up to reality and kill the toilet-to-tap boondoggle.’  Further back in the archives, in 2006 the sentiment was even blunter: ‘your golden retriever may drink out of the toilet with no ill effects. But that doesn’t mean humans should do the same.’  Fortunately, in the intervening years the UT has got religion, or at least education, about water scarcity and the real science about recycled wastewater.  Now the message matches reality: indirect potable reuse produces a higher-quality water source than anything being imported into San Diego currently.

One area environmentalists, taxpayers, elected officials and even the media have always agreed on is the issue is one of education.  That’s why we’ve supported and fought for a public education campaign to go with the pilot project.  Hopefully, when that campaign gets into full swing later this year, the Editorial Board will be first in line to testify to the power of science and a little persistence.

Clearing the air about desalination

Environmental groups challenging the Carlsbad Desalination Plant scrutinize the project because as proposed it’s the region’s most expensive and energy intensive water supply option. As one of the environmental groups leading the charge in challenging the Carlsbad Desalination Plant, we’re clearing the air about a few misconceptions.

Truth #1 Our cases have merit.

Procedural deficiencies at every reviewing agency have marred the approval process for the plant. While some suggest we are engaging in superfluous lawsuits, this desalination plant will be the largest in the western hemisphere and may set precedent for all other projects. We must ensure it is as protective of our environment as possible. Yet, our regulatory agencies have taken an “approve first, ask questions later” approach that could lead to disastrous consequences.

Our efforts, and those of our partner organizations, have already improved the project dramatically by ensuring carbon offsets and wetlands mitigation to offset some impacts from the proposed project.

Truth # 2 We don’t oppose desalination.

We support a comprehensive water policy – prioritizing how we get and use our water based on cost, environmental and energy impacts, and reliability. First, we need to exhaust conservation and water efficiency efforts. After the City of San Diego instituted mandatory water use restrictions last year, outside water use dropped 13 percent.  In a county where nearly 50 percent of our water goes to residential use (60% of that for landscape irrigation), conservation can provide huge savings.

Second, we need to aggressively pursue water reuse. The City of San Diego is currently exploring Indirect Potable Reuse, which recycles wastewater to drinking water standards above that of our current supplies. Rainwater harvesting, grey water and non-potable water reclamation provide other opportunities to access hundreds of millions of gallons of recycled water daily.

Both conservation and reuse are cheaper, more energy efficient than desalination and can dramatically reduce ocean pollution without killing fish in the process.

Truth # 3 Desalination is the most expensive way to enhance local water supplies.

Conservation saves consumers money by reducing water and energy bills. Augmenting local reservoirs with recycled water uses the same treatment technologies as desalination but at 40 percent of the cost. And while Poseidon continues to claim on its website that its project will be developed at no expense to taxpayers, the truth is the project will receive $350 million over the next 25 years in public Metropolitan Water District subsidies and has a pending $530 million request in tax-free Private Activity Bonds to finance the project.

Truth # 4 Desalination is also the most energy intensive water option for San Diego.

Estimates show that 19 percent of California’s energy usage is for the treatment, movement and delivery of water. Between 3 and 5 percent of the state’s energy is used simply to move water from northern to Southern California, but desalination requires more. It also uses one third more energy than recycling wastewater.

Truth #5 If it sounds too good to be true, it probably is.

We’ve been asked to stand aside and support public opinion. However few important battles (civil rights, environmental protection, etc.) have been won without taking unpopular positions. The project’s popularity is based on the allure of a seemingly inexhaustible ocean resource and the small fortune Poseidon has paid in public relations and lobbying efforts to promise everything to everybody: for San Diegans, an endless supply of cheap water; for taxpayer/consumer groups, a guarantee of no subsidies; for organized labor, good union jobs; and for environmental groups, full environmental mitigation (the company claims the plant will be a net benefit for wetlands and ocean habitat). Poseidon is San Diego’s real-life Santa Claus!

So, if you are asking yourself, “how does this add up?” you’re ahead of the folks that have approved the project to date. A better question may be, “why did so many appointed officials approve this project (almost always overruling staff recommendations) without asking these tough questions in the face of such obvious contradictions?”

This is the question we are trying to resolve through our challenges.

We all want the same thing for our region—a dependable, affordable and sustainable water supply. Rather than make decisions in a crisis, we’d like to see our region make strategic decisions that protect our citizens and environment from unnecessary costs and harm. That’s why we need to develop a more thoughtful, comprehensive water policy for the region that prioritizes lower-cost, lower-impact alternatives like conservation and efficiency and reclamation. Desalination should be a last resort in our water portfolio.