How to Test Water Quality at Home: Your Complete Guide

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The list of possible contaminants is very extensive, many of which can exist naturally in a variety of water sources. While not all of them are harmful, the ones that are can be very debilitating if consumed.

And the effectiveness of water purification systems can vary greatly depending on the type of contaminant which is precisely why testing is so important. You need to know what’s in the water before you can know how to treat it.

In this section, we’ll have a look at the different types of contaminants, what makes them dangerous, what levels are considered safe, and how to test for them.

The EPA categorizes contaminants according to their nature. These are physical contaminants, chemical contaminants, and biological contaminants.

Physical contaminants in water

Physical contaminants are more commonly found in groundwater and surface water sources which can include sand, silt, and other large debris particles—they're mostly filtered at the source and typically don’t make it far enough through the water system.

These contaminants are generally visible to the naked eye and don’t require further testing unless testing for certain physical properties such as turbidity or TSS, which we’ll explore later.

Most physical contaminants follow the EPA’s secondary standards since they’re less likely to cause illness in humans and more likely to cause problems to the water system.

Biological contaminants in water

The biological contaminants category refers to living microorganisms that exist in the water supply which include bacteria, viruses, and protozoa. Biological contaminants are commonly present in surface water sources such as lakes and rivers—likely due to fecal particles from animals.

Biological contaminants can also exist in shallow wells with a water table closely connected to a stream or in water distribution systems with poor sanitation practices. Developing regions with unregulated sanitation often experience many biological contaminants in the drinking water supply.

Because of their high potential for causing severe illness in humans, biological contaminants are regulated according to the EPA's primary standards.

Bacteria: 0 ppm (0 mg/l)

Bacteria are single-celled organisms made up of a variety of different species. Some of the most common waterborne bacteria are e. Coli, Legionella, Salmonella, and Shigella.

Due to the wide variety of bacteria that can exist in water, testing for each species individually is impractical. Therefore, testing for widespread indicator bacteria such as coliforms is a more suitable approach.

Coliforms are a group of closely-related bacteria that exists throughout the environment and are very easy to test for. While not necessarily harmful on their own, their presence in the water supply may indicate the presence of other harmful bacteria as well. Testing for Total Coliforms may help identify if further testing for more dangerous bacteria is needed.

All bacteria should have a presence of 0 ppm (0 mg/l) according to the EPA's primary standards.

Viruses: 0 ppm (0 mg/l)

Viruses are the tiniest of waterborne pathogens, affecting the DNA structure of human and animal cells. Unlike bacteria, viruses require a host to reproduce.

Some of the most common waterborne viruses are Hepatitis, Norovirus, and Rotavirus. Contracting a waterborne virus can make one extremely ill with symptoms of vomiting and diarrhea.

All viruses should have a presence of 0 ppm (0 mg/l) according to the EPA's primary standards.

Protozoa: 0 ppm (0 mg/l)

Protozoa are a group of microorganisms that are parasitic in nature, requiring a host to reproduce. Protozoa are larger in size than bacteria and viruses and often have protective membranes, making them more resistant to disinfection than other pathogens.

Like bacteria and viruses, protozoa are typically found in surface water sources where animal feces may be present.

All protozoa should have a presence of 0 ppm (0 mg/l) according to the EPA's primary standards.

Chemical contaminants in water

The chemical category of contaminants is certainly the most diverse group of contaminants on this list, ranging from naturally occurring elements to man-made chemicals.

Because there is such a wide variety of chemical contaminants that can exist in the water supply, both naturally and synthetically, a first-level testing method should be applied first to get a general idea of the presence of potential contaminants.

A home testing kit would be a great way to get a general idea of the structure of the water. The chemicals that are present can be further tested at a laboratory to get exact levels and thus better treatment options.

Organic vs Inorganic

Chemical contaminants are classified as either organic or inorganic. While these terms may seem to refer to whether a contaminant exists naturally or is man-made, it actually refers to its chemical makeup.

Inorganic compounds refer to any chemical that lacks the carbon element while organic compounds include the carbon element.

Inorganic Chemical Compounds

Inorganic compounds often come from rock formations within the earth’s crust and are therefore more common in groundwater than in surface water sources. Some inorganic compounds such as calcium and magnesium are beneficial for human consumption at low doses, others such as arsenic are highly toxic.

Problematic Elements:

Iron: < 0.3 ppm (0.3 mg/l)
Manganese: < 0.05 ppm (0.05 mg/l)

Like the minerals that cause water hardness, these problem elements are common in groundwater sources and are more of an aesthetic nuisance than a health concern.

Iron and Manganese can cause discoloration to the water and piping system.

Heavy Metals:

Arsenic: 0 ppm (0 mg/l)
Cadmium: < 0.005 ppm (0.005 mg/l)
Copper: < 1.3 ppm (1.3 mg/l)
Lead: 0 ppm (0 mg/l)
Mercury: < 0.002 ppm (0.002 mg/l)

Heavy metals can cause numerous health problems in individuals if consumed. These health problems can include neurological issues, digestive issues, liver disease, and cancer.

Heavy metals can either exist naturally in the water supply, enter the water supply through industrial contamination, or be leached into the water supply via corroding pipes.

Fluoride: < 2 ppm (2 mg/l)

While fluoride can be found naturally in groundwater and surface water sources, some municipalities add fluoride to the public water supply as a dental benefit. Small amounts of fluoride have been proven to have some benefits in strengthening teeth but too much fluoride can cause some serious health issues.

Nitrates: < 10 ppm (10 mg/l)
Nitrites: < 1 ppm (1 mg/l)

Nitrogen exists naturally in soil and is an active ingredient in gardening fertilizer. Bacteria in the soil convert Nitrogen into Nitrates/Nitrites, a consumable form for plants.

Excess nitrates/nitrites in the soil can leach into the water supply, causing health problems for humans.

Organic Chemical Compounds

While the term “organic” may seem to indicate a naturally occurring substance, it merely refers to the presence of the carbon element. Ironically, many substances which include the carbon element are actually man-made—existing as pesticides, industrial byproducts, and pharmaceuticals drugs.

Because of its close relation to industrial and agricultural byproducts, often resulting in the pollution of water sources, organic compounds are often found in surface water sources in close proximity to potential contamination sites. Some organic compounds can even be found in municipal water sources.

Some organic compounds can pose a serious health risk if consumed, often resulting in neurological or gastrointestinal disorders or even cancer.

Organic compounds are further divided into two groups: VOCs and SOCs.

VOCs

Benzene: < 0.005 ppm (0.005 mg/l)
Carbon tetrachloride: < 0 ppm (0 mg/l)

VOCs, volatile organic compounds, are compounds that vaporize easily into the atmosphere. These include industrial chemicals such as benzene and carbon tetrachloride.

SOCs

Glyphosate: < 0.7 ppm (0.7 mg/l)
Atrazine: < 0.003 ppm (0.003 mg/l)

SOCs, synthetic organic compounds, are less likely to vaporize into the air. These include agricultural herbicides and pesticides such as Glyphosate and Atrazine.

Other Water Properties

Hardness

We’ve addressed the basics of hardness earlier when mentioning the beneficial inorganic compounds of calcium, magnesium, and potassium. While these elements aren’t necessarily harmful to consume—and can, in fact, have health benefits in small amounts— excess concentrations of these minerals can cause water hardness.

Water hardness is the over-concentration of minerals that can cause build-up within the water pipes and cause calcium deposits on faucets, showerheads, and other fixtures.

Water hardness can also reduce the efficiency of soap lathering and can cause irritation to sensitive skin and hair.

While not a health concern, hardness is more of an aesthetic and functional problem that can require expensive repairs if left untreated.

pH

pH measures how acidic or basic the water is on a scale of 0-14. A pH of 7 is considered neutral. Anything higher than a 7 is considered basic while anything lower is considered acidic.

Measuring the pH of the water is useful for many applications including gardening, aquarium care, hydroponics, and aquaponics.

pH can also be a factor with water hardness and iron treatment. A pH of greater than 8.5 can indicate a hardness problem as it can mean a higher concentration of calcium and magnesium.

A higher pH level can also make the treatment for iron oxidation much easier as iron turns ferric at pH levels greater than 7.0.

Lower pH levels can cause corrosion of water pipes and leach heavy metals into the water supply.

Testing for pH can be done easily with home test strips.

The EPA sets a standard range for pH levels at 6.5 to 8.5.

TDS / Electroconductivity

TDS, or Total Dissolved Solids, refers to the total amount of dissolved inorganic minerals that are within the water. Dissolved solids cannot be seen with the naked eye as they’ve been broken down into their simplest chemical form.

TDS generally consist of inorganic salts, including calcium, magnesium, potassium, sodium, bicarbonates, chlorides, and sulfates, and oftentimes small amounts of organic matter.

An example of TDS can be seen when comparing ocean water with spring water. Ocean water has a very high level of TDS evidenced by the high concentration of salt. Spring water has a lower level of TDS as it generally consists of moderate levels of calcium, magnesium, and other minerals.

Measuring TDS is a great way to get an idea of the structure of the water as it informs you of how much “stuff” is in there. While TDS measurements don’t necessarily tell you the exact measurement of each chemical, high concentrations of TDS can indicate the need for further, more extensive testing.

TDS is measured by a TDS meter that tests the electroconductivity of the water. Water itself isn’t electroconductive, but it’s the minerals within the water that allow it to conduct electricity. A higher level of dissolved solids within the water will give a higher electroconductivity reading.

TSS / Turbidity

Where TDS measures the Total Dissolved Solids within the water, TSS measures the Total Suspended Solids within the water.

Suspended solids generally refer to a collection of larger particles that haven’t dissolved into the water such as sand, silt, and larger chemical compounds.

Turbidity refers to the clarity of the water in the presence of these suspended solids. Water with high turbidity will appear very cloudy and murky while low turbidity appears clear.

Measuring turbidity is important because high turbidity can often indicate the presence of harmful pathogens. Bacteria, viruses, and protozoa are able to find refuge in large particles such as sand and silt, making it harder to disinfect.

UV purification devices often require a sediment filter to reduce turbidity before applying ultraviolet radiation. Large particles of sand can often block the UV light from killing pathogens, rendering it less effective.