Water Quality

What’s the Black Gunk on My Fixtures?!


Common Causes and Ways to Remove Black Slime on Your Faucets

Sludge...slime...gunk–whatever you call it, you probably don’t want it near your drinking water. It’s sticky, it often smells, and it can leave you puzzled. On Tips for Taps, we’ve already addressed common causes of white residue on fixtures, but now it’s time to come over to the dark side…welcome to the world of black residue.

Black residue on faucets and fixtures is a very common problem and we’re here to answer:

  1. What causes black slime?

  2. What are the health effects of black residue?

  3. How you can get rid of the black gunk?

What Exactly is the Black Slime on Your Faucet?!

Before we get into the exact cause of the gross gunk, let’s take a step back and look at what flows from the tap. Along with H2O, tap water often contains dissolved minerals. Two of these minerals are iron and manganese.

Iron and manganese are both naturally occurring, non-hazardous elements found throughout the earth’s crust. As water travels through soil and rock, it can dissolve minerals containing these elements and holds them in solution. Most drinking water contains traces of dissolved iron and manganese. While they don’t produce a health risk, elevated iron and manganese concentrations can be a nuisance in water supplies–producing an unpleasant taste and off-putting odor. Iron and manganese in drinking water are not known to have any health impacts. Because they are chemically similar, manganese and iron often create similar aesthetic problems–which includes black film, gunk, or sludge. The sticky, slimy, stinky residue can make itself at home nearly anywhere water flows in your home.

Whether it accumulates in the faucet aerator, around the tub drain, inside the toilet tank, or even inside your tea kettle–black slime is usually due to bacteria that feeds on oxidized iron and manganese in your water supply.

Is Black Slime on Fixtures Dangerous for Your Health?

There are no federal primary drinking water standards set for either manganese or iron because their presence in drinking water is not associated with health effects, however there are regulations regarding secondary standards for both. These standards are set to fight nuisance problems (e.g. black slime) and aesthetic issues (i.e. taste, odor, color).

Manganese and Manganese-related Bacteria:

The U.S. EPA  recommends maintaining a manganese concentration at or below 0.05 parts per million (ppm) in drinking water. Neither manganese nor manganese-related bacteria are considered dangerous at the levels that typically occur in drinking water. Manganese exposure from water and food (our largest source of exposure) are not known to have a negative health effect. In fact, manganese is an essential nutrient and is required by the human body in small amounts. Similarly, manganese bacteria is categorized as non-pathogenic.  Some evidence does suggest that if manganese is inhaled in high concentrations over time, it can lead to neurological issues–but this is rare and not caused by drinking water.

Iron and Iron-related Bacteria:

Like manganese, iron (and related bacteria) are not dangerous to human health. Drinking water standards for iron are set based on potential nuisance and/or aesthetic issues. The EPA recommends a secondary maximum contaminant level (secondary MCL) of iron in tap water at 0.3 ppm.

While iron-related bacteria often produce reddish-brown slime, when they react with naturally occurring tannins (organic matter from vegetation) it frequently forms black, sludgy residue. This is why many people spot black slime inside their tea pots–as tea contains a high concentration of tannins.

How to Get Rid of Black Slime on Your Fixtures

Although black slime may have a few other causes  (i.e. oxidizing pipes or dissolving rubber seals in your water heater), iron- and manganese-related bacteria are the common culprits (especially in homes supplied by a private well). Subsequently, if you want to know how much manganese or iron are in your tap water, you must test.

Once you’ve confidently identified the presence of iron- or manganese-related bacteria, it’s time to solve the problem once and for all. Unfortunately, online research often points you toward temporary treatment measures, rather than lasting fixes. The temporary “fixes,” such as replacing pipes and regularly cleaning the affected area, will cost you time and money–but will not solve the problem. Because the root of the problem stems from the water supply itself, you must focus your attention there (i.e. the cause) rather than the slime (i.e the effect).

If you are on a private or shared well:

Shock chlorination might be the answer. Take a look at our comprehensive, step-by-step guide to shock chlorination here. Just remember: It is nearly impossible to kill all of the iron- and manganese-related bacteria in your well water system. The bacteria will eventually re-grow, so you may want to repeat the treatment from time to time. Feel free to reach out at hello@simplewater.usif you have any questions about the shock chlorination process!

If you are on a municipal water supply:

If the source of your bacterial problem is your city water system, then using at-home chlorination will not have the desired effect. The best treatment method depends on a variety of factors–such as the concentration and form of iron and manganese in the water, whether or not iron- or manganese-related bacteria are present, and how much water you need to treat. Each of these factors will help determine the most efficient/cost effective treatment method for you. Several treatment options include:

  1. Ion exchange water softener

  2. Sequestering

  3. Oxidizing filters

There you have it. The black sludge at the bottom of your drain is no longer a mystery. While certainly alarming to find, it shouldn’t leave you scared. It’s not as spooky as it seems–just a little stinky and slimy.

If you have black slime on your fixtures and want to test your water, send us a message (hello@simplewater.us) and our team of chemists, engineers, and water treatment experts can point you in the right direction! 























The Link Between Fluoride in Water and ADHD: Should You Be Concerned?

New Findings Suggest Fluoride Connected to An Increased Rate of ADHD in Children

Fluoride and ADHD.png

What is Fluoride?

All water contains some fluoride. Naturally occurring in water, soil, rocks ,and air, fluoride is a mineral also found in your bones and teeth. There have been numerous studies championing the benefits of fluoride on dental health and many U.S. water systems intentionally add fluoride to the drinking water supply.

While fluoride has been added to drinking water for upwards of 70 years in the United States, fluoride has come into the hot seat in recent years. A study published in the Journal Environmental Health found that areas with a higher proportion of artificially fluoridated water also had a higher prevalence of attention deficit hyperactivity disorder (ADHD) in children.

Additionally, a University of Toronto study suggests that higher levels of urinary fluoride during pregnancy are associated with an increase in ADHD-like symptoms in young children.

This begs the question: How concerned should you be about fluoride in drinking water?

What is Artificial Water Fluoridation?

Artificial water fluoridation is the practice of adding low concentrations of fluoride–0.7 parts per million (ppm)–to drinking water with the goal of improving dental health. Despite no legal mandate to fluoridate water, nearly 75% of the U.S. population of people had access to fluoridated water. It is widely considered to be a major factor in the 25% decrease in rates of tooth decay in the United States. While hailed as “one of public health’s greatest success stories” by some, the addition of fluoride to drinking water has always had its skeptics, and some people are downright opposed.

Does Fluoride Increase the Risk of ADHD?

For decades, health experts have disagreed as to whether artificially fluoridated water is toxic to the developing human brain. While extremely high levels can cause dental and skeletal fluorosis, it can also cause neurotoxicity in adults. Far less, however, is known about the impact on children's’ developing brains.  

What Does Research Suggest about the Risks of Fluoride?

Since a popular study on fluoride and neurodevelopment began in 1992, the percentage of the U.S. population that drinks fluoridated water has increased from 56 percent to nearly 70 percent. During that same time frame, the percentage of children with an ADHD diagnosis has increased from around seven percent to more than 11 percent.

Additionally, the 2018 University of Toronto study included the analysis of urine from women during pregnancy, as well as from their children from ages six to 12. Researchers examined how levels of fluoride in urine related to the children’s inattention and hyperactivity. After adjusting factors that impact neuro-development (such as gestational age at birth, birth-weight, birth order, sex, maternal marital status, smoking history, age at delivery, education, socioeconomic status and lead exposure), researchers were able to assign scores related to ADHD. They concluded that prenatal exposure to fluoride was associated with an increased frequency of inattentive behaviors and cognitive problems.

Finally, upwards of 40 studies show that children born in areas with elevated concentrations of fluoride (i.e. above the concentration typically used in U.S. public water system), have lower than average IQs. In fact, many studies demonstrate a significant link–showing that children in high fluoride areas had IQs that were seven points below those of children from areas of low concentrations of fluoride.

How Might Fluoride Increase the Prevalence of ADHD in Children?

The studies mentioned above suggest an association between fluoride and ADHD, however they do not prove causality. The question becomes, how might fluoride increase the prevalence of Attention-deficit/hyperactivity disorder? Below are some possible links:

Fluoride and Fluorosis:

Several studies suggest that children with moderate to severe fluorosis–i.e. The change in the appearance of tooth enamel due to excessive fluoride intake–can lead to a lower score on IQ tests and other measures of cognitive skills. According to a report by the Center for Disease Control  (CDC) suggests that 41% of Americans ages 12 to 15 have some form of fluorosis.

Fluoride and Lead Absorption:

The form of fluoride typically added to U.S. water supplies (fluorosilicic acid) can leach lead–a potent neurotoxin–from pipes. Research has shown that fluoride may increase the body’s ability to absorb lead and children in regions with highly fluoridated water frequently have elevated blood lead levels. Lead has been shown to play a role in ADHD.

Fluoride and Thyroid:

It’s been proven that fluoride impairs the activity of the thyroid gland, which is important for proper brain development.

Not Everyone Agrees on the Link Between Fluoride and ADHD

These findings have led many people to advocate against fluoride, however others were also eager to point out that this is just one study and may not definitively prove the causal link between fluoridation and ADHD. Limitations on the study include:

  1. Individual fluoride exposures were not measured

  2. ADHD diagnoses were not independently verified

  3. There may be other unknown factors (i.e. confounders) that explain the link

Should You Be Concerned About Fluoride in Drinking Water?

Despite the controversies surrounding artificial water fluoridation, the literature on the matter remains overwhelming positive. Fluoride is safe in low, controlled doses.

If you are concerned about your water quality (for any reason), Tap Score home water testing can help. Tap Score tests for fluoride, as well as 100s of other contaminants. For any questions, send us a message at hello@simplewater.us and our team f chemists, engineers, and water quality experts will be standing by!



























What is Reverse Osmosis (RO)?

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


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.


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.



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 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!

Is My Water Radioactive?

No, we’re not asking if your water is turning you into a monster...radioactivity in water is a real threat.


Radioactivity is not scary in the way that movies and popular culture depict. Sadly, it is much stealthier–it can cause irreparable damage to your body that stays hidden for years, or even across generations.

We are exposed to natural radiation in our daily lives (an example being bananas!). Radioactive particles, or radionuclides, are a part of the natural world–they exist in plants and animals usually as potassium-40 or radium-226. However, increased exposures to radiation occurs in our water or air when nuclear power plants, mining operations, or laboratories release radioactive materials into the environment.

Tap Score has written this guide to help you understand what radiation really is, what the associated risks are, and what types of radioactive elements are common in drinking water, and how they should be treated.

Getting the Terms Right: What Are Radioactive Particles?

Radiation refers to any process that emits energy in the form of electromagnetic waves or particles, such as light or sound. When we talk about radioactive particles, we are specifically referring to ionizing radiation. Ionizing radiation is radiation that causes an atom or molecule to lose electrons and become charged–this charged molecule is called an ion.

Radioactivity is “the act of emitting radiation spontaneously”. An atom can be radioactive when it is unstable and wants to dissipate some of its energy to reach a more stable form.

The different “forms” of stable or unstable radioactive elements are called isotopes. We distinguish these radioactive isotopes by their mass, which is attached to the end of the element name, like Uranium-238.

Radioactive Particles in Water are Alpha or Beta

Radioactive particles are present in rocks and soil, which usually serve as the path to enter groundwater. The two types of radioactive particles present in water are alpha and beta particles–which are present in different sizes and element types.

Alpha particles consist of two protons and two neutrons. Common examples in water are radium-226, radon-222, uranium-238, polonium-210, lead-206. While alpha particles cannot penetrate skin from the outside, they are active in the body and can cause damage if consumed.

Beta particles are radioactive particles made up of one electron. Common examples in water are strontium-90, potassium-40. Beta particles can penetrate the top layer of skin and cause burns. Beta particles likely cause more damage inside the body than alpha particles–they have more energy and can therefore travel farther into body tissue than alpha particles can.

Radioactive Particles in Water

We are concerned about naturally occurring radiation and additional radioactive particles that enter water from rock formations near mining sites, nuclear power plants, or laboratories. Radon, in particular, occurs in gaseous form in soils and can dissolve into groundwater or enter homes as a gas through the basement. Exposures to radon in both air and water are seriously concerning–here, we focus on exposure through drinking water.

Prevalence of Radioactive Particles: Private Wells at Higher Risk

The Environmental Protection Agency (EPA) sets standards for radionuclides in city treated drinking water, but if you are a well water user you are at a much higher risk for radioactive contamination. In a study conducted by the United States Geological Survey (USGS) on radioactive particles in well water, the most abundant element above the EPA health threshold was radon, appearing in 65% of wells. Uranium was present in only 4% of the wells– which makes sense because radon is produced as uranium decays.

Signs that You Have Radioactive Particles in Your Water

Unfortunately, there are no obvious signs of radioactive particles. The only way to identify radon and uranium in your water is through testing. As a company that tests water, we’ve made this pretty easy–our essential test and advanced well water tests include uranium testing, we offer a specific test for radon, and we’ve developed a full radiation test that measures Gross Alpha and Gross Beta particles.

How do radioactive elements in water affect my health?

Unfortunately, the effects from radioactive particles in water can cause cancer and even be fatal. While our skin can protect us against alpha particles in the environment, exposure to radiation through water is particularly dangerous because radioactive elements damage tissues and organs.

Radioactive particles cause damage by breaking chemical bonds essential to our body’s functioning. Changing bonds in a molecule drastically alters its ability to function. Radioactive particles can cause cells in our body to die or slow down their reproduction. If a group of cells crucial to bodily function dies, the effects can be fatal.

After the bonds of normal cells in the body are broken, they release electrons. This can create a chain reaction that can eventually impact DNA molecules. Mutations are consequent to DNA damage, which lead to cancer. And, if germ (sex) cells are mutated, the cancer can be transmitted to children long after the initial exposure. The results of a study done in Iowa show that towns with radium-226 present in their water supply had higher rates of lung, bladder, and breast cancer.

How to protect yourself from Radioactive Particles in Water


There are two primary treatment options for radioactive particles in water–carbon filters and ion exchange:

  • Carbon filters are one option for removing radium and strontium from drinking water. However, if radon is also present the filter must be changed very frequently–carbon can adsorb radon and lead to higher radiation exposure if radon is left to build up. As radon particles accumulate, they may fall out of the filter and back into the water stream.
  • Ion exchange can be used to treat uranium. However, ion exchange creates backwash that contains high concentrations of radionuclides, which makes disposal a concern.

Ultimately, the type of treatment you choose depends on what type of radiation problem you have.

Test Before You Treat

Though these health effects may be frightening, they can be prevented or at least mitigated.  Tap Score offers a Full Radiation Water Test to measures alpha and beta particles as well as a specific Radon Test to help you determine if you are at risk. We’ll also help you choose the right treatment options if you discover a problem. Picking the right filter matters to ensure you properly treat your water.

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







Why Is My RO Water Filter Leaking?

Do you have a reverse osmosis (RO) water treatment system? Is it not working properly? This is an article to help you determine why your drinking water filter is leaking and what you can do to fix your RO. 


If you own and maintain a reverse osmosis water treatment system in your home, then you’re probably already aware that things sometimes go awry. The water quality engineers at SimpleWater have pulled together a helpful list of the most common problems people have with their Reverse Osmosis water filters at home along with the most common solutions.

Reverse Osmosis: Problems, Solutions – A Quick Guide

Scan the headlines below for common symptoms, causes, and solutions to water filter failures. If you have questions about your water quality or your water treatment system, please don’t hesitate to reach out to our professional water testing team.

Scale forming on the membrane?

Cause: Failure of the antiscalant, acid dosing device, or pH monitor

Fix: Check your dosing equipment is working properly and monitor all changes in water quality before and after the RO system. Ask our team for help by emailing: hello@simplewater.us or clicking on our help page.

Iron accumulation on the filters and membranes?

(Leading to a high pressure difference and low permeate flow)

Cause: High iron content in raw water, corroding pipes, failure of media filters

Fix: Check pipes and media filters. Ask our team for help by emailing: hello@simplewater.us or clicking on our help page.

Bacterial film on filters and membranes?

(Leading to high pressure difference and low permeate flow)

Cause: Ineffective sanitization or biocide

Fix:  Sanitize all filters, perform microbiological analysis, check chemical dosing tanks; heck for biocide adsorption on carbon filters, check contact times and dose rates, select broad-spectrum biocide for organic content. Ask our team for help by emailing: hello@simplewater.us or clicking on our help page.

Organic or humic content on filters and membranes?

Cause: High organic content

Fix: Test the feed water for TOC and color Ask our team for help by emailing: hello@simplewater.usor clicking on our help page.

Membrane damage leading to high salts passthrough and high flux?

Cause: Chlorine overdosing

Fix: Perform chlorine tests, check dosing equipment, redox meters, bisulfite levels and the general location of dosing equipment. Ask our team for help by emailing: hello@simplewater.us or clicking on our help page.

High Salt Passthrough?

Cause: Failure of the O-ring at the permeate tube

Fix: Check conductivity in each vessel and membrane. Ask our team for help by emailing: hello@simplewater.us or clicking on our help page.

Bacteria and colloid fouling of micron-pre filters and membranes

Cause: Breakthrough of your media pre-filter

Fix: Wash your media pre-filters and add some biocide. Ask our team for help by emailing: hello@simplewater.us or clicking on our help page.