Stanford publishes a report on the balanced use of fracking

From Stanford University – Stanford-led study assesses the environmental costs and benefits of fracking


A strange thing happened on the way to dealing with climate change: Advances in hydraulic fracturing put trillions of dollars’ worth of previously unreachable oil and natural gas within humanity’s grasp.

The environmental costs – and benefits – from “fracking,” which requires blasting huge amounts of water, sand and chemicals deep into underground rock formations, are the subject of new research that synthesizes 165 academic studies and government databases. The survey covers not only greenhouse gas impacts but also fracking’s influence on local air pollution, earthquakes and, especially, supplies of clean water.

The authors are seven environmental scientists who underscore the real consequences of policy decisions on people who live near the wells, as well as some important remaining questions.

“Society is certain to extract more gas and oil due to fracking,” said Stanford environmental scientist Robert Jackson, who led the new study. “The key is to reduce the environmental costs as much as possible, while making the most of the environmental benefits.”

Fracking’s consumption of water is rising quickly at a time when much of the United States is suffering from drought, but extracting natural gas with hydraulic fracturing and horizontal drilling compares well with conventional energy sources, the study finds. Fracking requires more water than conventional gas drilling; but when natural gas is used in place of coal or nuclear fuel to generate electricity, it saves water. From mining to generation, coal power consumes more than twice the water per megawatt-hour generated than unconventional gas does.

Unconventional drilling’s water demand can be better or worse than alternative energy sources, the study finds. Photovoltaic solar and wind power use almost no water and emit no greenhouse gas, but cheap, abundant natural gas may limit their deployment as new sources of electricity. On the other hand, fracked gas requires less than a hundredth the water of corn ethanol per unit of energy.

Fracking’s impact on both climate change and local air pollution is similar to its impact on water, finds the study “The Environmental Costs and Benefits of Fracking,” published in the Annual Review of Environment and Resources.

Getting a fractured well going is more intense than for conventional oil and gas drilling, with potential health threats arising from increases in volatile organic compounds and air toxics.

But when natural gas replaces coal as a fuel for generating electricity, the benefits to air quality include lower carbon dioxide emissions than coal and almost none of the mercury, sulfur dioxide or ash.

Globally, though, relief to climate change is uncertain, the study finds. “While the increased gas supply reduces air pollution in U.S. cities downwind from coal-fired power plants, we still don’t know whether methane losses from well pads and pipelines outweigh the lower carbon dioxide emissions,” said Jackson.

In the eastern United States, fears of contaminated drinking water have raised more concerns than fracking’s water consumption. Gas and chemicals from manmade fractures thousands of meters underground very rarely seep upward to drinking-water aquifers, the study says. The real threats are failures in the steel and cement casings of wells nearer to the surface and the disposal of wastewater, the study finds. Numerous previous studies have shown that casings fail between 1 percent and 10 percent of the time, depending on geology and well construction.

Cases of groundwater contamination have been hotly debated, but the new study finds that the overwhelming evidence suggests it has happened, albeit not commonly. Is the methane contamination observed in drinking water a precursor to other toxins – arsenic, various salts, radioactive radium and other metals – making their way up slowly? The researchers do not yet know. A few recent studies suggest the answer could be “yes” in rare cases.

How oil and gas companies handle wastewater – fluid used to fracture the shale that flows back up the well and water unleashed with the oil and gas – shows the importance of state policies. “Wastewater disposal is one of the biggest issues associated with fracking,” said co-author Avner Vengosh, a professor of geochemistry at Duke University.

Most fracking wastewater in the United States is injected deep underground, and an increasing amount is recycled for subsequent drilling or sent to advanced water treatment facilities. However, a handful of states still allow the wastewater to be used for watering cattle, sprayed onto roads for dust control or sent to municipal water-treatment plants not equipped to handle the chemicals involved.

All bad ideas, according to the authors of the new survey, who work at Duke University, MIT, Ohio State University, Newcastle University, Los Alamos National Laboratory, the National Oceanic and Atmospheric Administration and Stanford. One study they cite found that the agricultural use of fracking wastewater killed more than half of nearby trees within two years.

Injection of wastewater deep underground presents its own problems, the study finds. The practice occasionally has caused earthquakes strong enough to be felt by human beings, while the fracturing of shale miles below the surface rarely has done so. The dangers of seismicity can be reduced, however, if energy companies follow basic guidelines and undertake careful monitoring.

The study highlights several policies and practices that could optimize fracking’s environmental cost-benefit balance, and it highlights the need for further research. For example, the direct impact on the health of nearby residents is virtually unknown. “Almost no comprehensive research has been done on health effects,” said Jackson, “but decisions about drilling – both approvals and bans on fracking –are made all the time based on assumptions about health risks.”


Additional co-authors include Thomas Darrah of The Ohio State University, J. William Carey of Los Alamos National Laboratory, Francis O’Sullivan of MIT, Richard Davies of Newcastle University and Gabrielle Pétron of the U.S. National Oceanic and Atmospheric Administration.

This article was written by Mark Golden, Precourt Institute for Energy, Stanford University


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The paper is here:
Interesting to note that it is stated that PV require no water for manufacture.
shows the processes gone through to get PV panels.
They look very water hungry to me.


what about pv during use? how the panels going to work if the dust is not cleaned off regularly?

When I was last in the semiconductor industry we recycled 90% of the water we used for PV manufacture.

Mike Bromley the Kurd

As do they with fracking water. In a process employed for six-plus decades.

“The Weston mothers suffered similar symptoms: hair loss, stomach and joint pain, body numbness and skin rashes.
Weston First Selectwoman Gayle Weinstein, a Democrat, warned the town will not be footing the bill for private well water testing or filtration systems.
“It is the homeowner’s responsibility to test the well water and then remediate it,” she said ”
Over 15 million U.S. households obtain their drinking water from private wells , which are not covered by the United States Environmental Protection Agency (EPA) regulations that protect public drinking water systems. Although the United States has one of the safest drinking water supplies in the world, sources of drinking water can still become contaminated through naturally occurring chemicals and minerals (for example, arsenic, radon), local land use practices (for example, pesticides, chemicals, animal feeding operations), malfunctioning wastewater treatment systems (for example, sewer overflows), and other sources. Contamination of a private well can impact not only the household served by the well, but also nearby households using the same aquifer”
Of course if you live in an area of fracking guess who you can blame and who has huge amounts of money.


“It is the homeowner’s responsibility to test the well water and then remediate it,” she said ”
Testing for sure. Once you find it’s polluted the “remediate” bit may be harder. Especially if you are up against someone “who has huge amounts of money”


you can always make yourself a solar still and purify out everything. I had friends who once had well trouble due to methane. That was long before fracking and probably before any oil well drilling in the area. Your biggest problem is that the ‘deep pockets’ drilling there might just be the solution to the well problem more often than it is the cause. Relieve the pressure down there and it’s much less likely for methane to push dangerous materials up to the water table.

The private well statement is misleading. Individual, private wells are not regulated under the same regulations for public drinking water systems. Why should they be? Private wells are regulated at the local (usually county) level. The wells must meet the EPA (unless local rules are more stringent) drinking water standards. It is not necessarily true that the owner is responsible for remediating the well, especially if the source of contamination is off-site and affects the aquifer.


I don’t believe there is any significant oil drilling in Connecticut, let alone fracing. So what is the purpose of your post? If you had some links to proven disasters in North Dakota, Wyoming, Texas or New Mexico as a result of fracing I might be more inclined to believe there is not an ulterior motive
There have been instances of oil wells being the source of contamination due to insufficient cementing of the surface casing but I don’t know of any instances where the process of fracing has contaminated any water aquifer. If you have more specifics, let us know.
And the use of the word “contamination” can be misused. The volume of chemicals used in the fracing process, besides water and sand is very small. What is recovered is generally reused or disposed of in an approved process. We still chlorinate and fluoridate our drinking water; is that contamination?

Leon Brozyna

The press release makes the study sound surprisingly balanced. The only bit I find exception with is:

much of the United States is suffering from drought

Once you get away from the southwest, much of the United States is not suffering from drought.
Seems to lay to rest most of the overblown dangers of fracking that opponents keep hyping.


Well, it seems to be taking a fairly impassioned look at whole issue which is encouraging. While it may put things into perspective, it does not seem to “lay to rest”.

Harry Passfield

Greg: If you truly think it an ‘impassioned look’ at the issue, what do you make of the different perspectives applied to ‘unconventional gas and coal use compared to PV: [my bold]

From mining to generation, coal power consumes more than twice the water per megawatt-hour generated than unconventional gas does.
Unconventional drilling’s water demand can be better or worse than alternative energy sources, the study finds. Photovoltaic solar and wind power use almost no water.

My point is that the study used a whole life water-use cycle for gas and coal but did not seem to apply the same strictures to PV’s life cycle (manufacturing, transport, etc)


That’s my take on it too Greg.

Their language use and their framing of the issues indicates that the author’s ‘impassioned look’ made to utilize every possible fracking scare possible.
1% to 10% casement failures… How many casements!? if one out of ten casements failed in one survey that is 10% but if another five hundred casements only showed five failures, that is 1%. Why weren’t the casements and failures totaled?
Well, that is sort of obvious, to make sure they got a large failure percentage number inserted.

“…Fracking’s consumption of water is rising quickly at a time when much of the United States is suffering from drought…”

Why the inclusion of ‘drought’? Except to make the water use sound irrational and potentially disastrous. Not that the East coast of America has experienced any unprecedented major drought recently.

“…Fracking’s impact on both climate change and local air pollution is similar to its impact on water, finds the study “The Environmental Costs and Benefits of Fracking,” published in the Annual Review of Environment and Resources.. …”
From the “The Environmental Costs and Benefits of Fracking” study referenced:
“Unconventional oil and natural gas extraction enabled by horizontal drilling and hydraulic fracturing (fracking) is driving an economic boom, with consequences described from “revolutionary” to “disastrous.” Reality lies somewhere in between. Unconventional energy generates income and, done well, can reduce air pollution and even water use compared with other fossil fuels. Alternatively, it could slow the adoption of renewables and, done poorly, release toxic chemicals into water and air. Primary threats to water resources include surface spills, wastewater disposal, and drinking-water contamination through poor well integrity…”

It appears that Stanford’s ‘paper’ is a slightly sexed up rehash of the same sort of alarmism from a NOAA influenced research. Note that NOAA’s influenced study the ‘good’ effect word is ‘revolutionary’ while the ‘bad’ effect word is ‘disastrous’. Neither word is really meant to instill comfort, especially concerning a forty plus year commercial activity that has yet to be ‘disastrous’ and isn’t very revolutionary. Typical less than honest research from the mal-adjuster’s crew.
Please also note the NOAA influenced study being rephrased uses sentences like “…it could slow the adoption of renewables..”.
This entire Stanford research article embellishes fracking adjectives with concern or fear, minimizes benefits and quietly tucks away quite a few outright fibs in between.
Oh yeah, research conducted using bad research; two wrongs make it right? Wrong!

Whoops! I must’ve mistyped the closing blockquote right after “poor well integrity…” making my following comments into another indented blockquote.


Correct, Leon. This is an excellent graphic & source of information – maybe Anthony would wish to add this to his “Reference Pages”?

Whatever happened to “peak oil”?? We were supposed to be out of oil and gas by now I heard.


reminds me of the peak coal book I found once. It explored the alternative energy sources like wind as well as the discussion of how many years supply was left. Seems the publish date was close to 1832. LOL

As I understand it, most of the ground water contamination comes from surface operations, not fracing at 10,000 feet below grade. I observed a fracing operation in 1967 as a summer engineering intern and fracing was not new then. There are 50 years of fracing experience, 50 years in which to find solid evidence of damage. Spraying roads and dead trees. Haven’t we learned from AGW – coincidence does not equal cause. Yes, fracing uses lots of water, compared to what? the gazzilions of acre feet for agriculture and the fertilizer & pesticide & herbicide infused runoff? comparatively speaking fracing is a benign drop in the bucket.

Steve from Rockwood

I visited a well drilled in 1929 where the geology log describes the well being “perforated” at the producing zone using nitroglycerin. But as the article clearly points out, it’s not fracing that creates the problem, it’s a poor seal between the well casing and formation that allows oil & gas to migrate upward through the well and into the aquifer.
The spraying the crops and killing the trees study seems tough to swallow. How can the crops survive and the nearby trees die?


Link to the study ??
Link to the press release ?

Leon Brozyna
Leon Brozyna

Whoops … the actual study isn’t due for another month … just the abstract is out.




No , there is a full pre-publication pdf available at the address you gave.

Leon Brozyna

Whoops (2) … the actual study is available on-line in advance:

Steve Keohane

Photovoltaic solar and wind power use almost no water
Not true for PVs, never saw an IC process that did not use huge quantities of de-ionzed water, and have lots of toxic waste depending on the process. Have they stopped using phosgene nerve gas? chromic acid? Been out of the loop for twenty years, the processes maybe cleaner, or not!


Nope, still do. All those nasty, horrible chemicals, including silane – a gas that explodes on contact with air, or hydrofluoric acid which goes through latex gloves and and human skin and tissues and attacks calcium in bones, and many other really, really bad things.

Steve from Rockwood

Getting a fractured well going is more intense than for conventional oil and gas drilling, with potential health threats arising from increases in volatile organic compounds and air toxics.

That sentence is probably baloney. How does a 10,000 ft conventional or fracked well even generate volatile organic compounds and air toxics at surface (during drilling? during production?). How does a fracked well generate more of this? Are they suggesting that shale gas (for example) formations contain more toxics than conventional gas formations?

Steve from Rockwood

Focusing on re-injecting fracked water into disposal wells is not a fair way of quantifying the environmental effects of fracking water. All the water that is injected into a disposal well contains something, otherwise you wouldn’t have to dispose of it. What percentage of water re-injected into a disposal well comes from fracking? I would bet it rounds down to near zero. You would need to discuss all the water being disposed and how that relates to earthquakes, not just directly attribute earthquakes to fracked water disposal.

Steve from Rockwood, most of the water injected into disposal wells is not from the fracking. It is coproduced with the oil and gas. These formations are not dry. This water is usually quite briny. Unlike conventional reservoirs where the water cut is always reinjected to maintain hydrocarbon production, it is not possible to reinject the watercut into fracked shale. Too impermeable. So the disposal wells utilize an adjacent permeable stratum, always deep below the surface freshwater tables, which are usually less than 1000 feet down. That way there is no possibility of groundwater contamination.

Steve from Rockwood

Thanks for the clarification.

Robert Doyle

The U.S. has passed the million mark and globally 2 million H.F. wells this year. The first was reported in 1949. So, the news reporting of a “novel” technology is absurd. What is novel and seems to be such a common sense idea occurred this summer in Canada’s British Columbia. The government decided to test the various aquifers as a benchmark before issuing drilling leases. I would have thought this would have been a standard practice. The U.S. states in the Marcellus play may find out they are not compliant with present EPA standards. If I owned an oil company, I’d insist on that test. I don’t own one… just stock in two.

Wayne Delbeke

I live in an oil and gas production area in Alberta. I had 5 wells and three springs on the farm with two wells and one spring on the remaining property I still own. There has been an oil well on my property since the 50’s and oil and gas wells all around me; with the last well a few hundred metres from my house drilled this year. I can’t count the number of times oil and gas companies have tested my water supply and my neighbour’s with no measurable impact.
For the life of me, I don’t understand the fuss.

It is almost impossible to completely “ruin” water. Common industrial water treatment processes can easily, though not cheaply, remove contaminants and recover pure water. Portable equipment exists to clean on site or at nearby facilities. Why do they re-inject? Well, duh, it’s cheaper!
Many agricultural sites are superfunds compared to fracing. Feedlots and dairies are prime sources of CO2, methane, and lots of contaminated water. Useful and abandoned farm equipment sits around dripping diesel, hydraulic fluid, gasoline, anti-freeze. Many of these operations think nothing of pulling a machine into a field and replacing the anti-freeze by dumping the old on the ground. Simply dump that used engine oil in a buried 55 gallon drum.
There are equally and perhaps more hazardous chemicals under your sink, in the garden shed, in your garage and car than what O&G producers use for fracing. Think the list is proprietary & secret? Just spend a few minutes w/ Google. The additives are not much and relatively speaking not that bad.

Jeff L

“Getting a fractured well going is more intense than for conventional oil and gas drilling, ”
This is mis-leading on a number of fronts but it would suggest that the industry could choose to pursue conventional targets instead of unconventional targets (those that require fracking as part of the process). Currently, there is virtually no conventional exploration in the onshore lower 48. The reason all of industry is chasing unconventional targets in the onshore lower 48 is that is the only game in town. Pursuing conventional targets isn’t a realistic option because there are so few conventional targets left. To those who would disagree with this statement, please list specific conventional plays in the lower 48 that could be pursued that aren’t being pursued now.

Uncle Gus

Fracking:Climate Change = Mariolatry:Christianity
A cult within the larger religion.


I happened to be in a small airport in NE PA. The two men across from me identified themselves as environmental scientists looking at the fracked gas wells. I asked that about the fracking process and what dangerous chemicals were used to frack gas wells. They gave me a list of chemicals that would be alarming to a novice. Nearly all of the chemicals were petro chemicals with benzene as one of the most toxic. I asked, “isn’t the purpose of fracking to discover petroleum and natural gas? Doesn’t the presence of these chemicals in the frack water demonstrate that they were successful?” There was no more conversation.

Joe Guyton

No mention here that leaked methane absorbs radiation in only two narrow bands which have already been saturated by water vapor, thus rendering such leakage as not a problem even if you consider AGW a real threat.


“Fracking’s consumption of water is rising quickly at a time when much of the United States is suffering from drought”
Just because the government insists that we are in a huge drought, does not make it true. Our drought areas are actually rather average and small. When areas claimed to be in drought by the government get loads of rain, they refuse to adjust their maps. Why?
The key with the government propaganda office is that if, say, Texas is 20 inches short on rain one year, but next year it goes back to normal, the propaganda office does not recognize the drought to be over. They insist that until the shortfall of inches of rain is realized as an excess of rain, the drought is not over. They insist that only flooding can cure a drought. This allows them to claim drought in areas that are certainly not suffering from lack of rainfall.
Most people’s definition of a drought being over is when the rainfall goes back to normal.

Since I have designed and performed hydraulic fracturing for over 30 years, I find it interesting that no one ever mentions that I have a identical goals with the fear mongers concerning placement of the fracture. Why would I want to expend as much as $1,000,000 to perform a process and not assure that the treatment is going where it will have the highest probability of producing oil or gas? Secondly, during the actual job, I monitor in a fashion that I can immediately see if the fracture is not going where I want and it takes less than 30 seconds to shut down the operation. Finally, if the job is shut down, we immediately flow back to avoid a costly clean out operation, which flows back any fluids that went in the wrong place. Although I have different motivations to avoid contamination, my goals are identical.

Jeff L

The thing is that those who oppose fracking don’t care if it is safe or not or that industry goals are compatible with their stated goals. This was just another fabricated crisis by the far left greens. The facts have never mattered to them. It was just another chance to try to alarm the uninformed to push their far left green agenda. Glad to see WUWT Give the issue some airtime so folks can learn the full story from posts such as yours.
. The parallels between the fracking debate & the CAGW debate are numerous.

Uncle Gus

One obvious non-parallel – the general public are actually involving themselves in the issue. In this it’s more like the GM debate. Chemicals, evil capitalists, and things that are an obvious part of people’s immediate environment.
We’ll see the alarmists moving more and more into territory like this in future.


There is a great deal of difference in how oil and gas waste water is handled in Canada vs. the U.S. Many things that are routinely done in the U.S. regarding water disposal would get you thrown in jail in Canada. The cost of more responsible water treatment and disposal is not that great so why not do it? It really isn’t that big of a deal.
What is also ironic is that things that farmers do in Canada to dispose of waste would result in an oil company getting large fines and hoose-gow time for it’s directors and executives. Double standard anyone?


You can tell the level of corruption to the science by the fact that scientists won’t just blurt out the truth every time someone mentions methane as a greenhouse gas…Methane cannot accumulate in the atmosphere because it has an atmospheric half-life of about 12 years. Levels can ONLY reach a level proportional to the overall increase in emissions and begin falling as soon as those emissions sources cease.


It’s expensive, but here’s one technology that’s ready to go now that will clean up fracking water.

Gary Pearse

To frack a formation, you have to use ~80% of the lithostatic pressure at the depth being fracked. Using much more could lead to problems of cracking beyond where you want to go. The rest of the pressure needed comes from the resource itself in the shale. This is carefully monitored since it isn’t profitable to have things go where you don’t want them to. The ‘anecdotes’ of damages to water wells and from earthquakes is mostly BS. It is not impossible to have an unexpected problem with any industrial process, but the rarity of it can be confidently stated by noting that fracking of conventional reservoirs has been going on since the first well was fracked in Kansas in 1947. We’ve only heard all the outrage and ‘anecdotes’ in the last half a dozen years when the greens learned about this venerable process when the success with shales got into the news. You can be sure that the greens main concern was accelerated production of cheap fossil fuels.
Regarding fracking chemical additives they make up ~0.5% of the frack fluid, the commonest being methanol and guar gum, along with lesser organic compounds that are the ones highlighted by enviromentalists. One, I can’t recall which, that has caused alarm is abundant in the browned surface of your breakfast toast and fried onions. Nevertheless, the industry has been working on green alternatives with success. One makes a gel out of propane which is produced from the well anyway, and there are waterless frac fluids that are simply liquified petroleum gases (LPG). I searched for links not associated with the petroleum industry and lo and behold found this one from National Geographic!!

Kip Hansen

For those who missed it above, the link to .pdf of the full study :
This is a the “Review in Advance — first posted online on August 11, 2014” version. Final version may contain changes.

Richard Sharpe

What happened to the Krugman parody?

Globally, though, relief to climate change is uncertain, the study finds.
They know upon which side their bread is buttered.


I saw a presentation on this topic by a Stanford geologist who may be a part of this study about a year ago, on campus in Palo Alto. He made (basically) the same points: shale gas is good, fracking is OK — *IF* the well casing is properly cemented. Which isn’t that easy to do, or test, was my impression — I’m a mining geologist who is familiar with the basics of petroleum extraction, but by no means an expert.
The audience reaction was interesting — these were Stanford faculty and interested laymen, plus a few students and a couple of “activists”. The discussion pretty quickly degenerated into the usual long list of things that *could* go wrong (but seldom do), from people who just don’t like heavy industry — as opposed to the *real* problem of properly cementing the well — which is expensive, and easy to screw up even if you’re trying to do it right.
I hope the industry is working on better ways to cement the wells, and to test that its been properly done. Otherwise, there will be headaches, and blowback from neighbors, and regulations they won’t like.


The surface casing has to be hydraulically isolating the surface aquifers from the production zones or it would not be possible to drill out from under the surface casing without losing all mud returns during the wells drilling process. The problems caused by bad surface cement are when an aquifer is near something like a coal seam that has some associated gas. There could be a channel in the cement sheath allowing communication between the two. This is rare but has happened. To repeat, if this channel were to occur between the bottom of the surface casing and the aquifer, it would not be possible to drill out without losing mud returns. Which makes it nearly impossible for a frac to enter a zone behind the surface casing. Hope I did not make that explanation too confusing.
At the start of a frac, there is a mini frac performed using a small volume of water pumped at a high rate. This mini frac tells the engineers overseeing the job if there are problems and what the formation parameters are. If there are problems, the job is stopped. These frac jobs are expensive and no one is going to pump one without a payout. There are usually no problems with the cemented production casing prior to a frac job. Prior to bringing in a frac company, the operator will run a cement bond log to insure that there is good bonding and that the cement has no channels. If there is a problem, remedial work is performed to ensure a good bond and isolation. To make sure the casing holds the necessary pressure during the job ( which can reach many thousands of PSI), a pressure test is done at a pressure greater than the frac is expected to produce. Relief valves are set a surface to make sure this pressure is not exceeded during the actual frac job.
As you can see, there are many levels of safety to ensure no contamination of the surface aquifers from fracing.

Cementing is part of completing any well, frac’d or not. After 50 years of application, can they still screw it up? Deep Water Horizon. Of course, but what’s the real track record.

Geologist Down The Pub Sez

If you think photovoltaic electrical generation using polycrystalline silicon cells, far and away the most common type, is free from the need for water, or that it generates not CO2, I suggest you visit a silicon smelter and the power station which generates the truly huge amount of electricity it consumes.

Dr. Strangelove

“Is the methane contamination observed in drinking water a precursor to other toxins – arsenic, various salts, radioactive radium and other metals – making their way up slowly?”
No. Expensive bottled mineral water contains radioactive radium, uranium, magnesium, sodium, potassium, etc. You pay a premium to drink these toxins.
“Almost no comprehensive research has been done on health effects,” said Jackson, “but decisions about drilling – both approvals and bans on fracking –are made all the time based on assumptions about health risks.”
There will be health effects if you drink the fracking fluid. You are advised not to do so. I guess activists already know the health effects of drinking sewage water. It can also contaminate groundwater but they don’t make a big fuss about its “unknown health effects.”