Why Is My Water So Hard?!?!?

 

Calcium
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Magnesium
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Who among us that live somewhere the water is hard haven’t asked that before ourselves? I certainly have, and I know why the water is hard.  It’s usually more a rhetorical cry of frustration than it is a cry for answers, but none the less, I thought someone out there might want to know a bit more about water hardness, both actual and perceived, so hold on to your hats, because here we go.  Water hardness is defined as the concentration of polyvalent cations, and is expressed as the equivalent concentration of calcium carbonate (CaCO₃) in mg/L.  Huh?  A cation is just an atom or molecule that has a positive electric charge and polyvalent means the positive charge is greater than +1.  So, for example, an atom of calcium dissolved in water is a polyvalent cation because it has a charge of +2, and is shown like this: Ca⁺².  Simple!  The most common polyvalent cations in drinking water that make up hardness are calcium (Ca⁺²) and magnesium (Mg⁺²), but can also include a whole host of ions such as iron, copper, zinc, nickel and others.  These latter elements are usually present in small enough quantities that they do not appreciably add to the hardness, however, so for the most part we can just consider calcium and magnesium.  The quantities for all these polyvalent cations that are included in hardness get converted to equivalent concentrations of calcium carbonate for simplicity and ease of comparing one sample to another.  Consumers like you and I for the most part don’t care about polyvalent/polyshmalent, cat-ions/dog-ions – all we care about is the spots on our glasses and that crusty stuff on our faucet.  Although hardness is a large part of that, it’s also affected by another measurement known as Total Dissolved Solids, or TDS.  That measurement is a bit easier to understand and is pretty much just as its name implies; it’s a measurement of all the stuff dissolved in the water.  It includes hardness, because the calcium and magnesium cations are a dissolved solid and therefore get included in TDS.  But it also includes things like sodium (Na⁺¹), sulfate (SO^-4), potassium (K⁺¹), chloride (Cl^-1) and others that can lead to those dreaded spots and crustiness when water is allowed to dry on glasses or fixtures, leaving the dissolved solids behind.  Many people also think of these compounds collectively as “salt”, and indeed when they dry, they do form salts such as the one we all know, sodium chloride or table salt, but also salts such as calcium sulfate or potassium chloride.  But fixture deposits and spotted dishes aren’t the only problems excessive hardness and TDS cause.  Over the years, calcium, magnesium, and TDS compounds can precipitate out of the water and form a coating on the insides of pipes in the distribution system or in home plumbing systems reducing the flow of water.  These precipitates can also collect in water heaters, reducing their efficiency, or plug up faucet aerators.  On the plus side, there have been some medical studies showing that the calcium and magnesium in hard water can be a significant part of the dietary intake necessary for good health, and that it can even be effective in lowering the incidence of cardiovascular disease.  Other medical studies have been inconclusive on this last point, so the jury is still out.   General hardness ratings are shown in the Table.  Where does all this stuff in the water come from?  For groundwater, the minerals in the water are those that have been dissolved from the local rocks and soils as the water moves through the aquifers beneath our feet.  Calcium, magnesium, and all the rest are very common in the local geologic structures, and water, being such a good solvent, is very effective at removing them.  Surface water, such as that in the California State Water Project, does not come in contact with rocks and soil for nearly as long as groundwater, so it has fewer of these elements dissolved in it, and therefore isn’t as hard.

Orange County Water District Groundwater Adventure Tour



Microfiltration units

Yesterday, November 10, 2011, the Orange County Water District (OCWD) held its annual tour of the Groundwater Replenishment System (GWRS), a state of the art system in Orange County, CA for recycling wastewater into drinking water and maximizing groundwater recharge from naturally occurring run-off in the Santa Ana River watershed. I was lucky enough to get a seat on the tour, which always seems to fill up fast, and along with about 150 other people, participated in the day long adventure.



Reverse osmosis cartridges



The GWRS is the world’s largest advanced wastewater purification system for indirect potable reuse.(1) The wastewater is purified using microfiltration (MF), reverse osmosis (RO), and advanced oxidation (AO) with hydrogen peroxide and ultra-violet (UV) light. The water that results meets all state and federal safe drinking water regulations for potable water. On the tour, they give you the opportunity to drink some, which I did; it tasted good, and I’ve had no ill effects, I assure you. However, rather than being used as a source of potable water directly, the water is either pumped into the ground near the coast as a barrier against seawater intrusion, or it is pumped to percolation basins so it can recharge the groundwater aquifer that underlies a large part of Orange County. The plant has a capacity of 70 million gallons per day (MGD). A 30 MGD expansion is currently in the planning stages, to be completed by 2014; and another 30 MGD expansion is planned for the future.



The far tap is the fully treated wastwater. Yummy!



The aquifer is also recharged by water draining from the Santa Ana River watershed. This recharge is enhanced by the use of rubber dams to divert the water into off-channel percolation basins, and by in-channel engineering that spreads the water out across the entire channel, maximizing the wetted area of the channel, which in turn maximizes percolation. The tour included a visit to one of the rubber dams and related off-channel features. These recharge efforts also include hundreds of acres of constructed wetlands in the area above Prado Dam, one of two large permanent dams on the river. These wetlands take water that drains from heavily agricultural areas, including large dairy farms, which is very high in nitrate, and allows natural biological attenuation to occur. The water leaving these wetlands, which flows into the recharge areas mentioned previously, has nitrate levels that are frequently non-detectable. This process prevents high nitrate water from percolating into the aquifer and causing widespread contamination. The tour group helped plant trees in the wetland area to help prevent erosion.

Inflatable rubber diversion dam on the Santa Ana River

The combination of the GWRS and the other recharge operations puts 230,000 acre-feet (AF) of water back into the aquifer every year; that’s almost half of the 500,000 AF of water that is used within the Orange County Water District.

It was a great tour, and a very educational day all around. I’d highly recommend it to anyone with an interest in water.

(1) The information is from the tour itself, and printed materials that were handed out.

Lead and Copper Sampling for Drinking Water Utilities

Lead & Copper sampling for drinking water systems is very unique in how the samples are taken; how they are reported; and how the data is used.



Lead
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For the most part, lead and copper samples are collected every three years. But, unlike the rest of the samples we are required to take, lead & copper samples must be collected by the customer, since they can only be collected from a tap inside the customer’s home. The tap it is collected from cannot have been used in the previous 6 hours, there can’t be a water softener on the system, and the customer must collect a full liter of water for the sample to be valid. Needless to say, asking your customers to do all of that can be problematic. Samples have to be collected this way because the lead & copper regulation is designed to test premise plumbing, and most lead & copper in peoples drinking water comes from either home fixtures, lead solder in old plumbing, or lead service lines. Every customer who provides a lead & copper sample receives a letter detailing what the results were for the sample taken from their home, as well as a lot of additional information about these elements that is mandate by the U.S. Environmental Protection Agency (EPA).



Copper
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There isn’t really a pass/fail for individual lead & copper samples, and there is no Maximum Contaminant Level (MCL) for this type of sampling. Instead, the regulations have an Action Level (AL) of 0.015 mg/L for lead, and 1.3 mg/L for copper. If the 90th percentile level for the lead & copper samples taken is above the AL, then the regulation requires that the water system take corrective action. Now, what the heck is a 90th percentile level? The 90th percentile means that 90% of the samples are less than that level, and 9% are greater. You determine the 90 percentile level by multiplying the number of samples you take by 0.9; so if you take 20 samples, then sample 18 is your 90th percentile sample. Then you put all the samples in order from least to greatest, and the value of your 18th sample is your 90th percentile level. Phew! Statistics makes my head hurt.

If a system exceeds the AL, then there are certain actions they have to take. These include a public education program about the health effects of lead & copper; implementation of corrosion control in the distribution system; and a lead service line replacement program where applicable. The health effects of lead include neurological damage in children, as well as high blood pressure and reproductive problems in adults. Excessive copper can cause liver and kidney damage in children, and various problems of the digestive system in adults.

If you would like to read more about the lead & copper rule, go to EPA’s web site at this address: http://water.epa.gov/lawsregs/rulesregs/sdwa/lcr/index.cfm

What to do With Your Prescription Drugs.

Today, October 29, 2011, is National Prescription Drug Take Back Day, sponsored by the U.S. Drug Enforcement Agency (DEA) (http://woodbridge.patch.com/articles/fed-agencies-disagree-on-whether-pill-flushing-harms-the-water-supply ). All across the United States, public and private entities of all sorts are providing an avenue for people to turn in those unused prescription drugs taking up space in their medicine cabinets, rather than throw them in the trash or flush them down the toilet. Federal Agency’s, however, seem to be at odds over the goals of this event, and others like it. The DEA has said it isn’t concerned with the environmental effects of dumping drugs down the toilet and having them flushed into the environment; they just don’t want them getting into the hands of those to whom they were not prescribed. That’s a worthy goal, but so is keeping the drugs out of the environment and our water; can’t they consider more than one goal simultaneously? The Food and Drug Administration (FDA) (http://www.fda.gov/forconsumers/consumerupdates/ucm101653.htm ) is not only OK with throwing them in the trash or flushing them, they recommend it, and don’t think it poses any threat to the health of the environment or those who have to drink the water somewhere down river, so to speak. That seems a bit short sighted and contrary to a growing list of research, at least when it comes to the environmental effects (http://e360.yale.edu/content/feature.msp?id=2263 , http://blogs.ei.columbia.edu/2011/10/05/pharmaceuticals-in-the-water-supply-is-this-a-threat/ ). And the EPA is adamantly against throwing them away or flushing, acknowledging that they are a threat to the environment and that, even though no human health effects have been proven, maybe it’s a good idea to be cautious until we know more (http://water.epa.gov/scitech/swguidance/ppcp/index.cfm ).

It would be nice if all three of these agencies could come to terms with all the reasons not throwing prescription drugs in the garbage or flushing them down the toilet is a good idea, and speak with one voice on the matter, but that may be too much to ask of them. All you and I need to know is that for lots of reasons, it’s a good idea to take those drugs to an official drop off location rather than do anything else with them.

California Public Health Goals

On Friday, July 28, the California Office of Environmental Health Hazard Assessment, or OEHHA (people just say “Oh-we-ha” for short – sounds like something you’d say at a rodeo), set the Public Health Goal (PHG) for chromium 6 at 0.020 ug/L. That will start the process moving forward toward setting a Maximum Contaminant Level (MCL) here in the state of California. But what is a PHG and how are they set by this funny sounding group, OEHHA? For a chemical compound or element that is suspected of having adverse health effects, studies need to be conducted – lot’s and lot’s of studies. These studies can be conducted by OEHHA themselves, or they may use data from other studies conducted by health effects professionals and groups all over the country or even the world. These studies test for carcinogenic (cancer causing) and non-carcinogenic health effects, and many of them focus primarily on those sub-sets of the population that are most at risk, which usually means pregnant women, children, and the elderly. Studies are usually conducted on animals, and then the data is extrapolated to humans, but data may also be obtained from humans in areas where people are actually exposed to the study compound or element because it’s already present in their drinking water or food source. OEHHA looks at all these studies and through the magic of toxicological statistics (at least it seems like magic to me), they come up with a number that they define as the PHG. This number is designed to represent the estimated “one in one million” lifetime cancer risk level for the compound or element in question. This means that for every million people who drink two liters of water with that level of the compound or element daily for 70 years, no more than one person would be expected to develop cancer. The “one-in-one million” risk level is widely accepted by doctors and scientists as the “negligible risk” standard. One of the difficulties with setting these PHG’s is that many times, the data from all those health effects studies is not as straight forward as it may seem. There is a lot of interpretation that goes on, and the OEHHA, like most health effects groups, tend to be conservative in how things are interpreted, resulting in very conservative numbers. Of course, this also results in a good deal of controversy, discussion, and misunderstanding surrounding any PHG. Once a PHG has been set, the process for determining an MCL begins, and that must take into account a lot of other information, such as whether the compound or element is present in drinking water; if laboratory methods exist to detect it in drinking water; and if there are best available technologies (BAT) available to treat for it at a reasonable cost.

California Public Health Goals

On Friday, July 28, the California Office of Environmental Health Hazard Assessment, or OEHHA (people just say “Oh-we-ha” for short – sounds like something you’d say at a rodeo), set the Public Health Goal (PHG) for chromium 6 at 0.020 ug/L. That will start the process moving forward toward setting a Maximum Contaminant Level (MCL) here in the state of California. But what is a PHG and how are they set by this funny sounding group, OEHHA? For a chemical compound or element that is suspected of having adverse health effects, studies need to be conducted – lot’s and lot’s of studies. These studies can be conducted by OEHHA themselves, or they may use data from other studies conducted by health effects professionals and groups all over the country or even the world. These studies test for carcinogenic (cancer causing) and non-carcinogenic health effects, and many of them focus primarily on those sub-sets of the population that are most at risk, which usually means pregnant women, children, and the elderly. Studies are usually conducted on animals, and then the data is extrapolated to humans, but data may also be obtained from humans in areas where people are actually exposed to the study compound or element because it’s already present in their drinking water or food source. OEHHA looks at all these studies and through the magic of toxicological statistics (at least it seems like magic to me), they come up with a number that they define as the PHG. This number is designed to represent the estimated “one in one million” lifetime cancer risk level for the compound or element in question. This means that for every million people who drink two liters of water with that level of the compound or element daily for 70 years, no more than one person would be expected to develop cancer. The “one-in-one million” risk level is widely accepted by doctors and scientists as the “negligible risk” standard. One of the difficulties with setting these PHG’s is that many times, the data from all those health effects studies is not as straight forward as it may seem. There is a lot of interpretation that goes on, and the OEHHA, like most health effects groups, tend to be conservative in how things are interpreted, resulting in very conservative numbers. Of course, this also results in a good deal of controversy, discussion, and misunderstanding surrounding any PHG. Once a PHG has been set, the process for determining an MCL begins, and that must take into account a lot of other information, such as whether the compound or element is present in drinking water; if laboratory methods exist to detect it in drinking water; and if there are best available technologies (BAT) available to treat for it at a reasonable cost.

What is a contaminant?

When most people think of contaminants, they think of some nasty chemical that’s polluting the land or water; something that leaked out of a tank somewhere; that was illegally dumped along some lonesome road in the middle of the night; or that is the result of the manufacture of some industrial chemical. And in some instances, any or all of those scenarios may very well lead to contamination of the water supply. But if you look at the EPA web site where they discuss and list all of the “contaminants” that they currently regulate in drinking water, ( http://water.epa.gov/drink/contaminants/basicinformation/index.cfm ), you will also find a lot of compounds that are naturally occurring; no one dumped them, manufactured them, or otherwise “polluted” the environment with them. They are every bit as much a part of the environment as the water itself. That doesn’t mean they can’t be harmful – arsenic is naturally occurring, but ingest enough of it and it can still kill you. Contrary to so many marketing campaigns that make you believe that “natural products” are somehow inherently safe, they can in fact be just as, if not more harmful than anything created by man. When I was taking Botany in college, someone asked my professor what the definition of a weed was. His response was that a weed is any plant that is somewhere you don’t want it to be. Likewise for drinking water, saying something is a contaminant doesn’t mean it’s the result of some toxic spill or other pollution. It means that, no matter what the source, it’s just something in the water that we don’t want there at more than a certain level.

Unregulated Contaminant Monitoring Rule 3

The 1996 amendments to the Safe Drinking Water Act (SDWA) require that EPA establish criteria for a program to monitor unregulated contaminants and identify no more than 30 contaminants to be monitored every five years. Known as the Unregulated Contaminant Monitoring Rule, or UCMR, the proposal for the third Unregulated Contaminant Monitoring Rule (UCMR 3) was signed by EPA Administrator, Lisa P. Jackson, on February 17, 2011. All Public Water Systems (PWSs) serving more than 10,000 people and 800 representative PWSs serving 10,000 or fewer people would monitor for these 28 contaminants during a 12-month period some time between January 2013 through December 2015. Groundwater only systems would have to sample twice, with each sampling event 6 months apart, while surface water systems would have to sample 4 times, with each sampling event being 3 months apart. The contaminants to be tested for can be divided into Hormones, Volatile Organics, a Synthetic Organic, Metals, an Oxyhalide Anion, and some Perfluorinated compounds. This last group of compounds is particularly interesting. They are used in products such as Teflon, Scotchgaurd, and other stain, oil, or water-resistant products. They are extremely persistent in the environment, and have been found in blood samples from people almost everywhere researchers have looked.

Radon - Isn’t that Superman’s Home Planet?

No, actually that was Krypton. Radon is an odorless, colorless, tasteless radioactive gas. It is the heaviest of all gasses, about 8 times heavier than air, and is naturally occurring from the radioactive decay of uranium. The U.S. Environmental Protection Agency (US EPA) and the Surgeon General's Office have estimated that more than 20,000 lung cancer deaths are caused each year by radon, making it the second leading cause of lung cancer in the United States. It is usually found in conjunction with uranium in igneous rock, such as granite, and in soil, but in some cases well water may also be a source of radon. The US EPA's proposed Radon Rule applies to all community water systems that use groundwater or mixed groundwater and surface water supply sources. The Radon Rule includes a two pronged approach that allows states and water suppliers to reduce radon risks in indoor air while protecting public health from the highest levels of radon in drinking water. The proposed rule includes the following provisions:

-A Maximum Contaminant Level (MCL) Goal of zero;

-An MCL of 300 picocuries per liter (pCi/L);

-And an Alternative MCL (AMCL) of 4,000 pCi/L.

pCi is the abbreviation for picocurie, the standard unit for radiation, named after Marie and Pierre Curie for their pioneering work on radioactivity.

The AMCL provision of the rule applies to water systems that adopt and comply with a Multimedia Mitigation (MMM) educational program aimed at reducing household indoor/air health risks from soil and tap water. The AMCL of 4,000 pCi/L is based on the National Research Council recommended estimates of 0.4 pCi/L as the outdoor background level in air, which is equivalent to 4,000 pCi/L in water. If a water system chooses not to adopt an MMM program, they would have to comply with the MCL of 300 pCi/L in all source water. Santa Barbara County and Ventura Counties are the two counties in California with the highest potential for harmful levels of radon to exist as identified by the US EPA. This rule is still in the proposal phase, and has not yet become a regulation.

Radon - Isn’t that Superman’s Home Planet?

No, actually that was Krypton. Radon is an odorless, colorless, tasteless radioactive gas. It is the heaviest of all gasses, about 8 times heavier than air, and is naturally occurring from the radioactive decay of uranium. The U.S. Environmental Protection Agency (US EPA) and the Surgeon General's Office have estimated that more than 20,000 lung cancer deaths are caused each year by radon, making it the second leading cause of lung cancer in the United States. It is usually found in conjunction with uranium in igneous rock, such as granite, and in soil, but in some cases well water may also be a source of radon. The US EPA's proposed Radon Rule applies to all community water systems that use groundwater or mixed groundwater and surface water supply sources. The Radon Rule includes a two pronged approach that allows states and water suppliers to reduce radon risks in indoor air while protecting public health from the highest levels of radon in drinking water. The proposed rule includes the following provisions:

-A Maximum Contaminant Level (MCL) Goal of zero;

-An MCL of 300 picocuries per liter (pCi/L);

-And an Alternative MCL (AMCL) of 4,000 pCi/L.

pCi is the abbreviation for picocurie, the standard unit for radiation, named after Marie and Pierre Curie for their pioneering work on radioactivity.

The AMCL provision of the rule applies to water systems that adopt and comply with a Multimedia Mitigation (MMM) educational program aimed at reducing household indoor/air health risks from soil and tap water. The AMCL of 4,000 pCi/L is based on the National Research Council recommended estimates of 0.4 pCi/L as the outdoor background level in air, which is equivalent to 4,000 pCi/L in water. If a water system chooses not to adopt an MMM program, they would have to comply with the MCL of 300 pCi/L in all source water. Santa Barbara County and Ventura Counties are the two counties in California with the highest potential for harmful levels of radon to exist as identified by the US EPA. This rule is still in the proposal phase, and has not yet become a regulation.

Fluoride – it’s more than just toothpaste!

©2011 Inorganic Ventures, Inc.

Fluoride.  It’s good for your teeth and bones!  It’s a communist mind control plot!  It prevents cavities!  It’s highly toxic!  These arguments have raged for many, many years over the practice of adding fluoride to drinking water, and will likely rage for many years to come.  Fluoride is the (-1) oxidation state of the element fluorine, and if you don’t remember about oxidation states, see the previous article on chromium (VI).  It does indeed help prevent cavities by forming an acid resistant coating on your teeth which is less likely to break down in the presence of the acids formed by plaque causing bacteria in your mouth.  And it can be toxic in high enough doses; but just like with most things, it’s the dose that makes the poison.  A little can be good, too much can be bad. The effects of fluoride on tooth decay were first discovered in the late 1800’s as scientists began researching the cause of the tooth streaking and mottling people get when exposed to high concentrations of naturally occurring fluoride.   It was also noticed that in these same areas, the incidence of tooth decay was a great deal lower than the average.  It didn’t take long before someone put two and two together, and by about 1945 municipalities started adding fluoride to the drinking water in an attempt to prevent tooth decay.  By the early 1950’s, studies had been conducted that showed significant reduction in the number of cavities in those areas where fluoride was being added.  And to this day, not a single one of those areas has been over-run by communists!  Public health and wellness organizations, such as the American Dental Association and the Centers for Disease Control, still recommend the addition of a small amount of fluoride to drinking water in those areas where it is not naturally occurring.  Fluoride has been in the news quite a bit recently in the United States because changes as to the recommendations on the amount of fluoride to be added to drinking water have been proposed.  Currently, the U.S. Department of Health and Human Services recommended range is 0.7 mg/L to 1.2 mg/L, but they are proposing to change it to just 0.7 mg/L, making it the same as the current recommendation from the Centers for Disease Control.  The EPA is also reviewing the Primary Maximum Contaminant Level (MCL) for fluoride, which is currently 4.0 mg/L, and the Secondary Maximum Contaminant Level (SMCL), which is 2.0 mg/L; California has its own primary MCL of 2.0 mg/L.  There is some fluoride in almost all groundwater, but generally it is below the current MCL’s and SMCL’s.  However, there are many places in the U.S. where the fluoride levels may be at or slightly exceed 0.7 mg/L.  If this level were to become an enforceable standard, then many water systems would have to implement fluoride removal treatment, which can be quite costly.

A little hexavalent chromium information.

©2011 Inorganic Ventures, Inc.

On December 20, the Environmental Working Group (EWG) released a report on a “study” they did regarding chromium (VI) in drinking water.  Since then there have been a lot of newspaper and other media reports coming out talking about the same thing, so here’s some background info on the whole issue.  Chromium (VI), which you’ll also see as chrome(VI), chrome-6, chromium-6, Cr (VI), hexavalent chromium, and many other variations on that theme, is a form of the metallic element chromium, which you used to be able to find on the bumper of every car.  Other uses for this metal have included plating of other metallic parts; manufacturing stainless steel; producing dyes; as a wood preservative; and as an additive for anti-corrosion purposes.  The (VI) or 6 part is a chemical designation that refers to what’s called the oxidation state of the element, which relates to the number of electrons the atom has. In this case, it is the highest oxidation state of chromium, the others being (II) and (III), with (III) being by far the most common. Although too much chromium in any state would not be good to eat, it is the highest oxidation form, chromium (VI) which is most reactive, and therefore of greatest concern from a health perspective. Small quantities of chromium (III) are actually required by all of us for proper sugar metabolism, but because chromium (VI) is so much more reactive, it can be disruptive to cellular metabolism and is a proven cancer causing agent when inhaled; it’s effect when ingested at low levels is still open to debate.   Although there is no EPA or state regulation requiring monitoring or treating for Cr (VI), a Public Health Goal (PHG) of 0.02 ug/L has been proposed in California.  Once a PHG has been formalized, then the process for determining an MCL will begin, and will take into consideration the economic and technical aspects of treating for this compound.

What the Heck is Perchlorate?

With the problems with perchlorate in many areas of the United States that have been in the news and that many, if not all of you, have heard about, you may be wondering what this chemical is and why it’s a problem. So I thought I’d talk a little bit about that, as well as some rather peculiar relationships between perchlorate and another chemical a lot of people in the drinking water and waste water business work with every day – more on that later.
Perchlorate is the most highly oxygenated form of chlorine – a chlorine atom with 4 oxygen atoms attached (see chart below). Usually, the more oxygenated something is, the more unstable and reactive it is. But perchlorate is quite stable, although definitely reactive, and having a stable molecule that packs a lot of oxygen atoms and is normally found as a solid is what makes it so important in manufacturing. Of course, when it dissolves in water is when it’s a problem for many of us.

Perchlorate is valuable as a source of oxygen for combustion, which is why the solid rocket boosters of the space shuttle contain 350 metric tons of the stuff. That’s also why it’s widely used in road flares, fireworks, and other explosives, like the detonators that fill the airbags if your car is in an accident. When perchlorate gets into the groundwater or surface water and then into our drinking water, it can have serious health effects. Perchlorate is an endocrine disrupting compound (EDC) in that it affects the proper uptake of iodine by the thyroid gland, a part of the human endocrine system. Improper thyroid function can lead to osteoporosis, as well as problems with metabolism and body temperature regulation, among other things.
A related, but less highly oxygenated compound that is use every day in many drinking water systems to disinfect the water supply is hypochlorite, generally applied as sodium hypochlorite, a liquid, or calcium hypochlorite, a solid. Hypochlorite is a chlorine atom with one oxygen atom attached (see chart), and is an excellent disinfectant, ensuring that the water we drink is free of the harmful pathogens, such as cholera, that plague so many people in the world. But hypochlorite can change form and add oxygen atoms as it ages, changing into chlorite and chlorate, and eventually becoming perchlorate. That’s one reason it is recommended that hypochlorite is never stored for more than 30 days, because small amounts of perchlorate may be formed given the right conditions.