water treatment

Arsenic and Water Treatment

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Testing your water and detecting arsenic at any concentration is never good news, but rest assured there are reliable steps you can take to safely protect your health by treating your water.

Arsenic is a well known human carcinogen that occurs naturally in groundwater. Public water systems are regulated by the US EPA to never exceed 10 parts per billion of arsenic concentration, but health research demonstrates that no level of arsenic is safe to drink. In fact, EPA proposed 5 ppb as a standard in 1996. Levels this low have shown statistically significant impacts on IQ among children, but economic requirements for setting maximum contaminant levels have kept the official threshold higher than levels harmful to health.

If you want to remove arsenic from your tap water, there are a few important things you need to know. We’ve broken it down into a simple FAQ sheet.

What is “total arsenic”?

Your total arsenic concentration is generally comprised of two common oxidation states (or forms), arsenic III (aka arsenite) and arsenic V (aka arsenate). In drinking water, we are usually worried about Arsenic V. If you drink water with Arsenic V, however, it is quickly converted to Arsenic III–which is more toxic and bioreactive inside your body.

Does the source of my water make a difference?

The source of your water makes a difference to the amount of arsenic III versus arsenic V in your water. This matters for choosing appropriate treatment options. If your water is coming from a community or public water treatment system and that treatment system uses chlorine for disinfection, then you can generally assume that most arsenic (if found in your water) is in arsenic V form.

If your drinking water comes from a groundwater well and there is no chlorination (or other oxidative step) installed as existing treatment, then you can’t be sure what fraction of your total arsenic is comprised by arsenic III or arsenic V. A type of water quality test called Arsenic Speciation can help determine if your total arsenic is mostly arsenic III or arsenic V.

Does reverse osmosis remove arsenic?

Reverse osmosis water treatment technology can reliably remove arsenic V but does not reliable remove arsenic III. If your water’s arsenic is all or mostly arsenic V then you can reliably use reverse osmosis technology to remove arsenic from your drinking water.

If your water’s arsenic is mostly comprised of arsenic III then you will either need a special treatment technology OR you will need an additional treatment step to oxidize arsenic III to arsenic V before using reverse osmosis for treatment.

Reverse osmosis is not the ONLY method of arsenic removal, companies like AdEdge and others provide other ion exchange and filtration-based treatment options.

Do I need whole home water treatment to remove arsenic?

Whole home water treatment for arsenic removal is NOT necessary unless you regularly drink water from many of the taps in the house. You can safely choose to treat only the water you ingest or use for drinking by installing a Point of Use filter at your main water source in the home or building (like under your kitchen sink). This can save thousands of dollars, because according to public health research, arsenic does not show an appreciable impact on health via showers, tubs, or brushing teeth (unless concentrations are enormous, >1,000 parts per billion).

It is important to note that no treatment technology can ever truly remove a contaminant 100%. Water treatment with reverse osmosis can remove arsenic as much as 98% however. Most professionals and public health research suggests trying to reduce arsenic intake by drinking water to less than 3 parts per billion. 

Get in touch with the Tap Score team here if you have further question about your water quality or about treating arsenic in your water.

Heavy Metals in Water & Soil: Methods for Treatment

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The ultimate faceoff: Human engineering versus plant power

We’re back with Part 2 on heavy metals! If you haven’t read Part 1 yet, be sure to do so to ensure you’ve got all the background info down.

As discussed in Part 1, you can be exposed to heavy metals through bioaccumulation in food. Though bioaccumulation often starts with microorganisms in aquatic environments, contaminants can also enter agricultural crops through contaminated soil or irrigation water in crop fields. Similarly, humans can be directly exposed to heavy metals through drinking contaminated water.

There are many methods available for reducing heavy metals at their source–before they enter our food and bodies. Chemically engineered methods such as reverse osmosis, ion exchange, and chemical precipitation have been in use for a while, but there are also some emerging technologies that utilize the natural power of plants to absorb heavy metals directly from the environment. Some of these technologies can only be used at treatment plants, while some of them are more consumer friendly and can be used at home. We review them both, below.

Chemically Engineered Methods

Contamination Pathway: Water

Reverse Osmosis

Used For: At Home Water Treatment for City & Well Water; Water Treatment Plants

Reverse osmosis (RO) can be used to treat many heavy metals such as chromium, copper, lead, and arsenic. RO technology uses added pressure to push water through a semipermeable membrane, which blocks contaminants larger than 0.0001 micrometers from passing through.

Removal rates depend on several factors including the post- and pre-treatment steps, but RO removal efficiencies are high for metals, with upwards of 99.4% removal for metals like cadmium and copper. Though reverse osmosis is a very effective method, it is expensive (systems costanywhere from $150-$1000) and creates a high volume of wastewater. Not only will this likely increase your water bill (by about $50/month), but the wastewater stream contains a high concentration of contaminants can harm the environment if not properly disposed of.

Ion Exchange

Used For: At Home Water Treatment for City & Well Water; Water Treatment Plants

Ion exchange is another common heavy metal treatment method, which can reduce nickel, mercury, lead, cadmium, chromium, and copper in water. When water passes through an ion exchange resin, heavy metal ions are attracted to the resin surface and easily swap places with charged surface particles called ions. The swapped ions are harmless ions such as hydrogen, making the discharge water safe to drink and use for irrigation.

As with all technologies, ion exchange has some drawbacks, including: it requires diligent cleaning (through backwash and brine regeneration) of the resin to work properly, it cannot handle highly concentrated metal solutions, it is not selective to heavy metals, and it is sensitive to your water’s pH. Ion exchange resins being “non-selective” means that they can also filter out beneficial ions in water such as minerals, like calcium and iron, that your body needs.

Chemical Precipitation

Used For: Water Treatment Plants

Chemical precipitation is one of the most widely used methods for heavy metal removal. Contaminated water is mixed with a chemical solution, often containing lime, that reacts with the heavy metal ions. This causes the heavy metals to precipitate into solids. The precipitate is then large enough to filter out, and the heavy metal removal is complete!

Chemical precipitation is well established and low maintenance, but also creates concentrated wastewater sludge and can require complicated chemical dosing.

Ecologically Engineered Methods

Contamination Pathway: Soil & Water

Phytoremediation

Used For: Water Treatment Plants; Soil Remediation Projects

Phytoremediation enompasses any method that uses plants to uptake contaminants from soil or water.  It is more affordable than chemically engineered methods and more environmentally friendly, because it does not create concentrated wastewater sludge that can harm ecosystems.

Engineered wetlands are an example of phytoremediation in action: water passes through and sits in wetlands while contaminants collect on the floor of the wetland and get taken up by plants.

However, phytoremediation is time consuming, limited by the age of the plant, root depth, level of contamination, weather conditions, etc, and there still exists a concern for proper contaminated plant disposal.

A few phytoremediation methods include:

Phytoextraction & Phytovolatilization

Phytoextraction refers to plants’ ability to uptake/absorb heavy metals through their roots and transport them to the above ground parts of the plant, called shoots. The shoots can then be burned to both generate energy and extract heavy metals from the ash to be recycled. Or, in the case of phytovolatilization, the heavy metals are released into the atmosphere.

Phytostabilization

Certain plant species can immobilize heavy metals present in soil and groundwater by “adsorption and accumulation in plant tissues, adsorption onto roots, or precipitation within the root zone” (Tangahu).  Once the plant has latched onto the heavy metals, they can no longer move throughout the soil or be swept away by erosion.

Bio-Sorption

Bio-sorption refers to the adsorption of contaminants onto modified agriculture such as hazelnut shells, pecan shells, maize cob or husk, rice husk, or jackfruit. The foods are heated into activated carbon, then used to adsorb heavy metals.

What about Contaminated Soil at Home?

Phytoremediation requires expertise to ensure that the correct plant species is being used and that contaminants are being removed effectively. At home, you’ll need a simpler approach–but you’ll want to know what’s in your soil first. Soil testing is an essential first step to understanding what is in your soil.

If you find you have contaminated soil with heavy metals, there are a few simple methods you can use to remediate the problem. You can create raised beds for your crops that are above the contaminated soil, or you can add a thick layer of organic material such as mulch or compost on top of your soil to create a physical barrier from the contamination.

Conclusion

Much water and soil treatment happens behind the scenes at treatment plants and soil remediation projects–but some of these methods are applicable at home. At Simple Water, we mostly focus on helping people protect themselves from heavy metals by providing advanced at-home tests for water and soil, so people can get a sense of what you’re dealing with and what type of treatment may be appropriate for their situation.

As always, if you have any questions, feel free to email us at hello@simplewater.us!

Source:

https://www.cdc.gov/healthywater/drinking/home-water-treatment/household_water_treatment.html

https://www.sciencedirect.com/science/article/pii/S0011916404001699

https://www.sciencedirect.com/science/article/pii/S0045653504001675

https://www.sciencedirect.com/science/article/pii/S1878535210001334

https://pdfs.semanticscholar.org/428f/d34c37f3b95900d80119e5726d3e17a73ace.pdf

https://www.hindawi.com/journals/ijce/2011/939161/

https://www.sciencedirect.com/science/article/pii/S1878535210001334

https://www.epa.gov/sites/production/files/2014-03/documents/urban_gardening_fina_fact_sheet.pdf

https://www.cdc.gov/healthywater/drinking/home-water-treatment/household_water_treatment.html

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4144270/

https://nepis.epa.gov/

https://www.cdc.gov/healthywater/drinking/home-water-treatment/water-filters/step3.html

https://www.homeadvisor.com/cost/environmental-safety/install-a-water-treatment-and-purification-system/

https://www.statista.com/statistics/720418/average-monthly-cost-of-water-in-the-us/

Risks of Distilled Water

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What is Distilled Water?

Distilled water is a type of purified water that has been boiled until it evaporates. The water vapor is then condensed back into liquid form, leaving the water devoid of impurities.

At first glance this sounds great. However, “impurities” don’t just include the unwanted things in your water. The term covers a wide range of dissolved and suspended solids–from contaminants to minerals. While yes, we all want our water contaminant-free, the distillation process is non-discriminatory removal process that strips water of the good and the bad.

This leaves some arguing that as a suitable drinking water choice, distilled water leaves somethings to be desired.

Potential Health Risks of Drinking Distilled Water

According to the World Health Organization report, there are a handful possible negative effects that come with drinking demineralized (i.e. distilled) water–WHO claims it “might not be fully appropriate for consumption” because distilled water:

  1. Can cause metals and other materials to leach from pipes and storage containers

  2. It doesn’t taste as good as tap water

  3. Can lead to low intake of essential elements and micronutrients

We’re going to breakdown these concerns below. The main point is this: while distilled water is better than contaminated water, it is not better than regular tap water and may even have negative health impacts.

Why does distilled water cause pipes and storage containers to leach undesirable contaminants?

If you store distilled water for drinking, you may be at risk of consuming parts of the container you store the water in. Because low- or demineralized water is molecularly unstable, it is “highly aggressive” to materials with which it contacts. Subsequently, distilled water can leach undesirable compounds from any material it comes in contact with.

Distilled water more readily dissolves plastics, (heavy) metals, and some organic substances from pipes, coatings, storage tanks and containers. As a result, you may wind up consuming them instead.

If you do drink distilled water, we recommend that you store it in glass.

Why does distilled water taste worse than regular tap water?

It is often reported that distilled water doesn’t taste as good as tap water. Some even claim it is less thirst quenching.

Why? Isn’t it just water?

When distilled water is created through the boiling process, the dissolved air within leaves the water. Subsequently, this results in a flat taste. Additionally, along with the loss of the dissolved air, calcium is also eliminated–which, when present, often contributes to water’s pleasant taste.

While neither flat taste nor lack of thirst-quenching are considered to be health effects, they could have some very real implications–as it may affect the amount of water one drinks.

How does distilled water impact nutrient intake?

While regular tap water is generally not a major source of nutrients, its contribution may be significant to your health–particularly when it comes to calcium and magnesium. As a World Health Organization (WHO) report notes, the typical modern diet may provide inadequate amounts of minerals and microelements. Subsequently, if faced with borderline deficiency of particular element, the relatively low intake of the element from drinking water may play a protective role in your health.

Elements in drinking water are usually present as free ions (rather than being bound to other substances when in food), making them more readily absorbed in the body.

In fact, the same WHO report goes on to discuss a handful of epidemiological studies from the past half century that indicate that water low in calcium and magnesium (also known as ‘soft water’) is associated with the following (when compared to hard water):

  1. Increased morbidity and mortality from cardiovascular disease

  2. A higher risk of fracture in children

  3. Certain neurodegenerative diseases

  4. Preterm birth and low weight at birth

What are the Uses of Distilled Water?

While we don’t typically recommend drinking distilled water, it certainly has its merits. Distilled water is often used for in laboratories for experiments, as well as for a variety of industrial applications. It is also a good choice for humidifiers, aquariums, and for use in cooling systems (as many many minerals found in tap water can damage lead-acid batteries).

What it Boils Down To

While we (generally) recommend drinking tap water over distilled water, this only holds true if you know what’s flowing from your tap. You should always test your water before making a definitive decision as to what is the best choice for you. If you find that  you have low-quality or contaminated tap water, then distilled water is a better (and safer) choice

Check our our water testing packages to make an informed decision or send us a message at hello@simplewater.us for more information! 


Sources:

https://www.livestrong.com/article/372479-what-are-the-dangers-of-drinking-distilled-water/

https://lifehacker.com/here-are-all-the-ways-you-should-be-using-distilled-wat-1821080543

https://www.medicalnewstoday.com/articles/317698.php

http://www.who.int/water_sanitation_health/dwq/nutrientschap12.pdf

https://sciencetrends.com/what-is-the-ph-of-distilled-water/

https://www.healthline.com/health/can-you-drink-distilled-water#side-effects

https://city.milwaukee.gov/water/customer/FAQs/tasteandodor/Why-does-boiled-water-taste-flat.htm#.W2uP9thKjaY

What is Reverse Osmosis (RO)?

Reverse Osmosis is an advanced water filtration technique, but is it for you?

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Finally! A detailed explanation for the type of water filtration you’ve probably heard most about, and for a good reason–reverse osmosis (RO) treats more contaminants than almost any other filter.

RO can filter out contaminants like arsenic, bacteria, lead, and fluoride. This makes it a popular treatment technology in water systems, but also at home. RO systems range from under-the-sink to point of entry (POE) installations treating the whole home’s water.

If you already have an RO and are trying to diagnose a leak or a problem with your system, hop over to our handy problem-identification guide about RO system leaks. For newcomers or interested-RO owners, Tap Score created this guide to explain how reverse osmosis works, which contaminants it does and does not remove, and what some of the pros and cons of an RO system are.

How does Reverse Osmosis Work?

Osmosis occurs in the natural world and is essential to many plants and animals’ life processes (an example being when plants absorb water from soil). During osmosis, water moves across a semipermeable membrane from an area with a low concentration of dissolved particles to an area with a high concentration of dissolved particles. A semipermeable membrane is a material that lets some atoms or molecules through while stopping others–similar to a screen door letting in air but keeping bugs out. This flow leads to an equal concentration of particles in water on either side of the semipermeable membrane.

Reverse osmosis, on the other hand, does not occur in nature. It requires added energy in the form of pressure to force water to move from an area of high concentration of particles to an area of lowconcentration of particles.

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The effect is to concentrate contaminants on one side of the semipermeable membrane (the waste stream) and produce freshwater for drinking on the other side (fresh water product).

What does an RO System Include?

Reverse osmosis itself only includes the passage of water through a semipermeable membrane. However, RO systems always contain additional pre-treatment filters and often post-treatment filters. These extra filters are referred to as “stages”. For example, if you see an RO system advertised as a 5-stage system, that means water passes through 5 stages of filtration before arriving at your faucet.

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Pre-treatment

Semi-permeable membranes are very sensitive–this means they are easily damaged if water is not properly treated before reaching the membrane. There are multiple kinds of pretreatment filters that water must pass through to prevent foulingscaling, and premature RO membrane failure:

  • Multimedia filtration/microfiltration is used to filter out sediment particles such as sand, clay, and plant matter/microorganisms. If these particles are not filtered out, they can cause fouling–they accumulate on the RO membrane and plug it up. 
  • Granular activated carbon (GAC) removes organic contaminants and disinfectants in the water such as chlorine or chloramines. Chlorine and chloramines are oxidizers and can react with the RO membrane and “burn” holes in it. 
  • Antiscalants/scale inhibitors are chemicals added to water to prevent scaling on the RO membrane. Scaling happens when dissolved compound concentrations exceed their solubility limits and precipitate out of the water and onto the membrane. A common example is calcium carbonate, or CaCO3, which occurs frequently if you have hard water. 

If pre-treatment is not used or maintained properly, fouling and scaling can decrease water flow across the membrane and decrease water quality.

Post-treatment

Post treatment can include an additional GAC filter to remove any last organic contaminants that still remain, remineralization/alkaline treatment, or UV treatment for bacteria.

What Does Reverse Osmosis Remove from My Drinking Water?

RO can treat inorganic contaminants such as (but not limited to):Arsenic

  • Asbestos
  • Nitrates & sulfates
  • Lead, aluminum, copper, nickel
  • Dissolved solids/salts

However, because all RO systems also contain carbon and sediment pre-filters, they can also filter some pesticides, algae, some bacteria & viruses, and other organic contaminants. (For a full list of RO treated contaminants click here).

Reverse osmosis does not remove molecules smaller than 0.0001 micrometers or molecules that are nonpolar, such as dissolved gases. Specifically, it does not catch:

  • Some pesticides/herbicides (1,2,4-trichlorobenzene, 2,4-D and Atrazine)
  • Some ions & metals (chlorine, radon)
  • Organic chemicals that weigh less than water (Benzene, Carbon tetrachloride, Dichlorobenzene, Toluene and Trihalomethanes (THMs))

Though some of these small particles may be caught by the carbon pre-filters, it is not guaranteed.

Common Complications Using Reverse Osmosis

There are a number of downsides to using reverse osmosis, including:

  • Increased water usage: Only 20-30% of the source water is discharged as clean water while 70-80% is discharged as more concentrated wastewater, so your water usage and bill will most likely go up.
  • Lot of upkeep: You must be very diligent about changing all of the pre-treatment filters on time–if chlorine is in your water and breaks through, you may cause permanent damage. RO membranes must also be sent away and cleaned by a serving company 1-4 times per year.
  • Difficult installation: A hole must be drilled in your home’s main drain pipe for the wastewater line, and in the countertop/sink for the faucet.
  • Water pressure: RO systems can decrease water pressure throughout your house.
  • Limited under sink space: Storage tank for treated water can take up under sink storage.
  • Can remove too much: Reverse osmosis can filter out good minerals from water such as ion and manganese. 

The Ultimate Question: Is a Reverse Osmosis System Right for Me?

If you have a problem with inorganic contaminants such as arsenic, fluoride, or nitrates, or if you have a high total dissolved solid (TDS) count, RO is likely a great option for you. If you have multiple water quality issues that include both organic and inorganic contaminants, reverse osmosis is a good option that will cover all your bases.

It is important, however, for you to know your water’s full chemical profile before installing a reverse osmosis system. Why should you test before you treat with RO? RO is expensive and time consuming–so you’ll want to make sure this is the right choice. Further, membranes can be damaged by certain contaminants present in your water, so knowing what type of pretreatment you need is essential, just like Tap Score’s Essential Water Test.

Have more questions? Feel free to email us at contact@simplewater.us!



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