Water Quality Testing

Vocabulary List

• Lead: a heavy, bluish-gray, soft metal, the chemical element of atomic number 82
  
  
• Probes: physically explore or examine (something) with the hands or an instrument
  
  
• Colorimetric: An instrument that measures the concentration of a known constituent of a solution by comparison with colors of standard solutions of that constituent - being a part of a whole
  
  
• Turbidity: the quality of being cloudy, opaque, or thick with suspended matter
  
  
• Hardness: the quality or condition of being firm or solid
  
  
• Concentration: the action of strengthening a solution by the removal of water or by accumulating molecules
  
  
• Standards: a level of quality or attainment
  
  
• Quality: general excellence of standard or level
  
  
• Groundwater: water held underground in the soil or in pores and crevices in rock
  
  
• Distribution: the way in which something is shared or dispersed among a group or spread over an area
  
  

Case Example

A small community noticed an unusually high number of cases of teenagers reporting severe abdominal pain and vomiting. Through a series of diagnostic tests, doctors discovered that the teenagers had high levels of lead in their blood. Further investigation by the health department revealed that all the students attended the same middle school that was built in the 1960s. An environmental health specialist was sent to the school to test the drinking water. Initial tests showed high levels of lead in the drinking water of several drinking fountains. Follow up testing concluded that the water entering the school had safe levels of lead but after the water flowed through the old lead pipes of the school, it became further contaminated with lead. Recommendations were given to replace the pipes in the school.

Water testing can be a valuable tool to help identify and remedy potential exposure to chemicals or metals in the drinking water.

Introduction

Water Quality Testing Techniques

Water quality testing can be conducted at many places including lakes, rivers, homes, schools, commercial buildings, and water treatment facilities. While there are many ways to test water quality, there are four methods that can be used for most testing.

Direct Reading Probes

Direct reading probes are instruments that provide instant results when their tips are placed in water. These instruments are generally easy to use although the sensors in the probe should be calibrated before use. An example of a direct reading probe would be a digital thermometer . Some direct reading probes can collect results for only one water quality, while there are some that have more than one sensor and can collect results for multiple water qualities. These are called multi use probes. An example could be a digital probe that tests both the temperature and pH at the same time.

Colorimetric Testing

A colorimetric test uses color changes in water to identify water quality characteristics or concentrations of substances in the water. There are two types of colorimetric tests: chemical and paper. Chemical testing requires adding drops of chemical to the water samples. Sometimes a colorimetric test will require multiple sets of different drops. Sometimes, the colorimetric test drops are added after the water changes to a specific color and the number of drops required shows what the concentration is in the water. Other colorimetric tests have a set number of drops and the resulting water color is compared to standard colors of known concentrations. Often, the darker the color, the higher the concentration in the water. Paper testing consists of paper strips that have chemical reagents applied to them. When the paper strips are dipped in water, the reagents will cause it to change colors. The color change is compared to standard colors of known concentrations. Paper testing strips can be for only one substance, such as pH, or can have multiple measuring points for as many as 15 different substances.

Light Refraction devices (spectrophotometers)

Light refraction devices shoot light rays through a water sample and measure the amount of light that is scattered and reflected back to the sensor. These are used to determine the concentrations of substances in the water. Usually, a small water sample is collected and placed inside the measuring device so that no other light can enter. Then the light is sent through the sample. Sometimes the spectrophotometer is built into a probe. These devices should also be calibrated before use.

Lab-tested samples

Sometimes water samples must be sent to a laboratory for testing. Care should be taken in collecting the samples so no contamination occurs. Depending on what type of testing is needed, the samples might need to be maintained in a cold temperature, out of the sun, or in opaque sample bottles.

Water Quality Testing Specifics

Temperature

Temperature can be tested using a thermometer, digital probe, multi use probe, and even an infrared thermometer, although the infrared thermometer can only test surface water temperatures and not internal water temperatures.

Drinking water temperature depends on personal preference. Optimum river temperature depends on the location and time of the year. High river water temperatures can lead to low dissolved oxygen, algae growth, and stress on aquatic species.

Turbidity

Turbidity can be tested using light refraction devices and direct reading probes. A Jackson Turbidity meter uses a candle and flat-bottomed glass tube to measure turbidity. Another method is to use a Secchi disk. The Secchi disk is a black and white disk that is lowered into the water until it is no longer visible. It is then slowly raised until the black-and-white pattern is visible. At that point, the depth of the disk is measured to determine the point where water is sufficiently turbid to obstruct visibility.

Turbidity is commonly measured in Nephelometric Turbidity Units (NTUs). The World Health Organization (WHO) recommends that turbidity in drinking water should ideally be kept below one NTU because of the recorded impacts on disinfection. Large well-run municipal supplies should be able to always achieve less than 0.5 NTU before disinfection and an average of 0.2 NTU or less irrespective of source water type and quality (WHO, 2017b). The United State Environmental Protection Agency (EPA) recommends that the turbidity in drinking water should not be higher than one NTU and samples for turbidity must be less than or equal to 0.3 NTU’s in at least 95 percent of the samples in any month (EPA, 2023).

Total Dissolved Solids (TDS)

Total dissolved solids (TDS) can be tested using direct reading probes and light refraction devices. The WHO states that the palatability of water with a TDS level of less than 600 mg/L is generally considered good (WHO, 2017a). The EPA secondary drinking water regulations list a standard of 500 mg/L (EPA, 2022b).

Salinity

Salinity can be measured using direct reading probes, light refraction devices, and paper test strips.According to the EPA, fresh water from rivers should have a salinity of 0.5 ppt or less (EPA, 2006).

Hardness

Hardness can be measured by direct reading probes, colorimetric testing, and paper test strips. Hardness is measured in parts per million (ppm) or grains per gallon (gpg). 17.1 ppm is equal to 1 gpg. If a reading is in ppm, it is easy to change it to gpg because it is only necessary to divide the ppm by 17.1. To go from gpg to ppm, it is only necessary to multiply by 17.1. Below are two examples:

How many gpg is 122 ppm?

        122 ppm/17.1 = 7.13gpg

How many ppm is 2.7 gpg?

         2.7 x 17.1 = 46.17

After testing for hardness, the results should be compared to the table below to classify the water. Results over 3.5 gpg are considered hard, and water softening is recommended.

pH

pH can be measured using direct reading probes, colorimetric testing, and paper test strips. The pH of most drinking water lies within the range 6.5–8.5. Surface and groundwater might have a lower pH, because of acid rain or percolation through limestone areas (WHO, 2007).

Dissolved Oxygen (DO)

DO can be measured using direct reading probes and colorimetric testing. Healthy water should generally have dissolved oxygen concentrations above 6.5–8 mg/L and between about 80—120% (Datastream, 2023). DO levels below 3 milligrams per liter (mg/L) are a biological concern and waters with levels below 1 mg/L are considered hypoxic and are usually devoid of life (EPA, 2022a).

Biochemical Oxygen Demand (BOD)

Measuring BOD is done by collecting a sample of water and initially testing the DO content, then storing the sample for five days before testing it again. The difference in the readings will show the five-day BOD.

A BOD level of 1–2 ppm is considered very good. There will not be much organic waste present in such a water supply. A water supply with a BOD level of 3–5 ppm is considered moderately clean. In water with a BOD level of 6–9 ppm, the water is considered somewhat polluted because there is usually organic matter present, and bacteria are decomposing this waste. At BOD levels of 100 ppm or greater, the water supply is considered very polluted with organic waste (CIESE, 2023). Most relatively unpolluted streams have a BOD that ranges from 1–8 mg/L (Delzer, G.C., and McKenzie, S.W., 2003).

Metals

There are many metals in drinking water that can be tested. It is best to know which metal you want to test for rather than conducting a general test for multiple metals. Some metals can be tested with simple paper test strips. All metals can be tested by sending water samples to a lab.

The EPA has listed maximum contaminant levels (MCLs) for several metals found in drinking water. Three of the more important metals in drinking water are arsenic, lead, and copper. EPA recommends controls if lead concentrations exceed an action level of 0.015 mg/L (Delzer, G.C., and McKenzie, S.W., 2003). The WHO recommends that lead in drinking water levels are below 0.01 mg/L and copper levels are below 2 mg/L (WHO, 2022).

Nitrates

Nitrates can be tested using colorimetric tests and paper test strips.

The WHO recommends nitrate levels in drinking water are below 50 mg/L (WHO, 2022).

The EPA national primary standards list drinking water levels should be below 10 mg/L (EPA, 2023).

Biologicals

A general biological test is conducted by placing flathead minnows in a sample of water to see if they can survive for seven days. This tests the air and nutrients and general health of the water.

Testing for biological contamination in water is difficult because there are so many bacteria, viruses, protozoa, and helminths that can be found in water. It is not practical to test drinking water for every type of pathogen. It is common practice, however, to test for the bacteria E. Coli as it is an indicator species of fecal contamination, which means if it is present, there may be other harmful pathogens in the water. One way to test for bacteria is by conducting a Heterotrophic Plate count, which is where water is placed in a petri dish and incubated, and the total colonies of bacteria are counted.

Testing for viruses, protozoa, and helminths is impractical in that it requires that large samples of water (100–500 gallons, 400–2000 liters) pass through tiny pore size filters before being looked at under a microscope, which takes a long time to conduct the testing. Unless there is a known pathogen that needs to be tested, it is far easier to just treat the water.

Drinking Water Testing Protocol

In cases where it is necessary to test drinking water for metals such as lead and copper, there is a standard protocol for conducting this type of testing. This protocol is a multi-day process that includes sending samples to a lab and reviewing laboratory results.

Protocol

Water sources include hand-washing sinks, dishwashing sinks, kitchen sinks, general purpose sinks, janitor sinks, drinking fountains, water bottle fillers, toilets, hose bibs (faucets), five-gallon water containers, and hard tapped lines such as water lines in fridges and coffee machines.

Drinking water sources include kitchen sinks and general-purpose sinks designed for providing drinking water, such as sacrament sinks at churches, drinking fountains, and water bottle fillers. Five-gallon (20 liter) water containers and hard-tapped lines such as water lines in fridges and coffee machines. Non-drinking water sources include toilets, hose bibs, and any other sink including bathroom sinks.

All drinking water sources must remain undisturbed overnight. If a source has been used, don’t test it. Cover it up and come back another day.

A sample sampling form is located with materials on the drinking water quality testing assignment.

Sampling numbers for the purpose of this class should follow the following format: CB-04-22-1Pb. The first two letters (CB) should indicate where the samples were collected. CB in the example stands for Clarke Building. The next four numbers give the date of the sampling, in this example, the sampling occurred on April 22. The last part of the numbering system is for the sample number and what is being sampled. In this example, the first sample is for lead. 2Pb would mean the second sample is for lead. 3Cu would mean the third sample is for copper. 4PbCu would indicate that the fourth sample is for both lead and copper.

It is necessary to collect the first drop of the water sample. If the first drop is missed, you must return on another day to resample that water source.

Each lab will have its own chain of custody form to fill out. A sample chain of custody form is found with the drinking water quality testing assignments. A chain of custody form filled out properly shows who had control of a sample at all times. Often this form is also used by the lab to show what type of sampling to perform on the samples.

It is best to personally deliver samples to a lab, but if they must be mailed, use a reputable mail service. Make sure the lab has proper accreditations to conduct the testing of your samples.

In this case, the action level is 15 ppb for lead and 1.3ppm for copper.

Requirements on how to write the drinking water testing report can be found in the appendices of this book.

Other water testing methods

When testing river water, one of the important factors to determine is what the overall water flow of the river is. Water flow is calculated using the equation Q=AV, where Q is water flow, A is the cross-sectional area of the river and V is the velocity of the water. The cross-sectional area of a river is calculated by taking the width of the river and multiplying it by the average depth. Average depth can be calculated by taking at least five measurements at different points spanning the river. The velocity of a river is determined by averaging the water velocity at least five points spanning the river. Water velocity readings can be collected using a flow meter.

Below is an example of how to calculate water flow. The first picture shows the width of the river and the depth at five points, while the second picture shows the five water velocity measurements. Calculate the overall river flow.

Average depth is (1.5 + 2.4 + 5.1 + 4.7 +1.2)/5 = 15/5= 3ft

Cross-sectional area is 3ft X 32ft = 96 ft2

Average Velocity is (12.1+10.2+7.5+8.2+11.4)/5 = 9.88 ft/m

Q=AV

Q= 96 ft2 X 9.88 ft/m

Q= 948.48 ft3 /min

Wells

Case Example

Heidi’s family grew up in a rural area surrounded by farms and cattle ranches. There was no city water system to hook up to, so they hired some farmhands to drill a well. Instead of drilling down to the second aquifer, the drillers hit a water table at about 12 feet (4 meters) deep, stopped, and put in the well. The well had no problem producing water for Heidi’s farm. Two years later Heidi had her first child, a boy. As he grew, he was quickly switched over to drinking baby formula. The milk-like powder was mixed into the well water and then put into a bottle for her son. One morning her son’s skin started to turn blue, especially around his mouth, face and cheeks followed by his hands. Heidi rushed her son to the hospital where a doctor ruled out congenital heart problems. After a series of questions to the mom, the doctor diagnosed the son with blue baby syndrome and asked the health department to test the family’s water source. The results showed extremely high levels of nitrates in the water. It was assumed that the nitrates came from runoff from the local farms and ranches that contaminated ground water near her house. Nitrates in drinking water can affect the body’s ability to process oxygen and the main symptom is the bluing of the skin.

It is important that wells are properly constructed and located in areas where minimal contamination can occur. Regular testing of wells can show if the water is safe for human consumption.

Introduction

Drinking water

Drinking water comes from two main sources: surface water and groundwater. Surface water is water taken from lakes, streams, rivers, and other sources on the surface of the land. Groundwater is taken from water sources underground. There are many advantages and disadvantages of using ground or surface water. Some of those are listed below.

Wells

The main way to get groundwater out of the ground is to construct wells. More than 100 million people in the US rely on a public supply well for their drinking water while 43 million people rely on domestic (private) wells as their source of drinking water (USGS, 2019a; USGS, 2019b). Over a third of the world’s population is supplied with drinking water from groundwater (International Association of Hydrogeologists, ). There are three major types of well that are constructed: dug or bored, driven, and drilled.

Dug or bored wells

If the ground is soft and the water table is shallow, then dug wells can work. Historically, dug wells were excavated by hand shovel to below the water table until incoming water exceeded the ability of the digger to remove the water. The well was lined with stones, brick, tile, or other materials to prevent collapse, and was covered with a cap of wood, stone, or concrete. They cannot be dug much deeper than the water table. Dug and bored wells have a large diameter and expose a large area to the aquifer, making them subject to contamination from nearby surface sources, and they go dry during periods of drought if the water table drops below the well bottom. (USGS, 2018). Dug wells are shallow at approximately 10–30 feet (3-10 meters) deep (EPA, 2022).

Driven wells

Driven wells are built by driving a small-diameter pipe into soft earth, such as sand or gravel. A screen is usually attached to the bottom of the pipe to filter out sand and other particles (USGS, 2018). Driven wells are cased continuously and shallow (approximately 30–50 feet (10–15 meters) deep). Though driven wells are cased, they can be contaminated easily because they draw water from aquifers near the surface (EPA, 2022).

Drilled wells

Most modern wells are drilled, which requires a drill rig. Drill rigs are often mounted on big trucks. They use rotary drill bits that chew away at the rock, percussion bits that smash the rock, or, if the ground is soft, large auger bits. Drilled wells can be drilled more than 1,000 feet (300 meters) deep. Often a pump is placed in the well at some depth to push the water up to the surface (USGS, 2018). Drilled wells have a lower risk of contamination due to their depth and use of continuous casing (EPA, 2022).

Well inspections

Inspectors often inspect wells as part of an overall water system inspection. An inspection can take several hours or days to complete, depending on the complexity of the water system. Water systems should be inspected every 3–5 years while water quality should be tested by the well owner on a yearly basis.

Opening Conference

When the inspector arrives to conduct the routine inspection, the first step is to go over the water system records. This includes discussion and review of the following: distribution system plans and maps, routine operation and maintenance records, monitoring history, future monitoring plan, and operator certification credentials.

Field Inspection of Water System

After the water system records have been discussed and reviewed, the surveyor will then take a tour of the water system. The tour will include an inspection of the well, treatment equipment, pumps, controls, water storage, and distribution system. If necessary, the inspector will collect water samples to send off to the laboratory for testing.

Closing Conference

After completing the walkaround inspection, the inspector should meet with the water system owner and share the initial findings of the inspection.

Written Report

Upon concluding the water system inspection, the inspector completes a final report, and a copy will be provided to the owner or operator. Any deficiencies identified during the inspection will be explained within the report. Systems are then required to take corrective action within the agreed-upon time frame.

The report should include the following:

• An introduction
• Narrative
• Methodology (if any testing was conducted)
• A results table (if testing was conducted)
• A table with the deficiencies and recommendations on any corrective actions

Examples of well issues

Well regulations are jurisdiction dependent, which means every city, county, state, or province may have their own regulations. Inspectors should learn and become familiar with the regulations in the area where they work. Below is a list of general well issues organized by specific categories.

Wellhead and casing

• Visible above ground
• Casing at least 12 inches (0.33 meters) above ground surface
• Area around well casing bermed or sloped away
• No cracks in or corrosion/damage to casing
• No voids or spaces around casing
• Electrical fully contained and not exposed

Well Cap

• Sanitary, sealed, water-tight conducted
• Bolts tight and secure
• Without any holes in the cap
• Presence of insects or vermin around well cap

Accessibility and Housekeeping

• Easily accessible for future repairs and service
• The area around the well is clean
• There is no rodent or pest harborage

Pumps

• Pump cycles less than six times an hour
• Pumps are in good repair without excessive heat, noise, vibration, odors, or leaks
• Spare pump parts should be available

Materials Storage

• Chemicals and materials stored in original and labeled containers
• Chemicals and materials are stored on leak preventing surface
• Materials are properly disposed
• No hazardous materials dumped on the ground
• Chemicals or materials are not stored within 50 feet (15 meters) of the well
• Vehicles or machinery are fueled on a concrete floor
• Avoid the use pesticides being applied around the well

Location of Wells (Wells should not be located near the following)

• Property boundaries, building foundations, or other wells
• Grazing animals, animal kennels, poultry buildings, or feedlots
• Bodies of water, such as lakes, streams, ponds, rivers, and swimming pools
• Wastewater disposal systems, septic systems, and sewer lines
• Gas lines and electrical lines, other than the line for the pump
• Private and public roads
• Cemetery or grave sites
• Landfills or garbage dumps

Here is a photo of a well that is full of garbage and not well maintained.

Here are two examples of wells where the area around them is kept well maintained and clean.

Protocol for collecting water samples at wells

Each jurisdiction has their own requirements for collecting water samples. Below is an example protocol that may be used in many areas or areas where there aren’t regulations.

Selection of Water Source

• Collect the sample as close to the well as possible.
• Collect the sample from a tap, faucet, or spigot that is regularly used and easily accessible.
• Do not sample from a garden hose. If a hose is being used, remove it and collect the sample at the faucet.
• Do not collect water that’s been through a water filter or treatment device.

Testing

• Wash and/or sanitize hands or use sterile gloves.
• Remove the cap from the collection bottle.
• Do not touch the inside of the cap.
• Do not set the cap down; keep it in the hand that is not collecting the sample.
• Keep fingers below the threaded part of the collection bottle.
• Do not rinse the collection bottle.
• Fill the bottle up to the indicated level, often 100mL.
• Replace the cap and tighten and seal.

Post-Testing

• Keep the collection bottles in a cool place such as a refrigerator.
• Fill out the chain of custody forms.
• Drop off the sample at the laboratory as soon as possible and within 24 hours.
• Wait for the results.

References

CIESE. (2023). Biological Oxygen Demand. Retrieved Feb 4, 2023, from https://books.byui.edu/-Jvwn

Datastream. (2023). A monitors Guide to Water Quality - Dissolved. Retrieved Feb 3, 2023, from https://books.byui.edu/-ZTWFy

Delzer, G.C., and McKenzie, S.W. (2003). Five-day biochemical oxygen demand: U.S. Geological Survey Techniques of Water-Resources Investigations. ().USGS.

EPA. (2006). Voluntary Estuary Monitoring Manual- Chapter 14 Salinity. (). https://books.byui.edu/-cpNF

EPA. (2022a). Indicators: Dissolved Oxygen. Retrieved Feb 3, 2022, from https://books.byui.edu/-KRSo

EPA. (2022b). Secondary Drinking Water Standards: Guidance for Nuisance Chemicals. Retrieved Feb 3, 2023, from https://books.byui.edu/-CvUY

EPA. (2023). National Primary Drinking Water Regulations. Retrieved Feb 03, 2023, from https://books.byui.edu/-QADo

International Association of Hydrogeologists.Groundwater – more about the hidden resource. Retrieved feb 08, 2023, from https://books.byui.edu/-MKET

Learn About Private Water Wells. Retrieved Feb 8, 2023, from https://books.byui.edu/-FuGe

SAFE DRINKING-WATER. (). https://books.byui.edu/-evJz

USGS. (2018). Groundwater Wells Retrieved Feb 8, 2023, from https://books.byui.edu/-KpNJ

USGS. (2019a). Domestic (Private) Supply Wells. Retrieved Feb 8, 2023, from https://books.byui.edu/-cUxU

USGS. (2019b). Public Supply Wells. Retrieved Feb 8 2023, from https://books.byui.edu/-yLcp

WHO. (2007). pH in Drinking-water -WHO Guidelines for Drinking-water Quality. (). https://books.byui.edu/-MpVK

WHO. (2017a). GUIDANCE FOR PRODUCING

WHO. (2017b). WATER QUALITY AND HEALTH -

REVIEW OF TURBIDITY:

Information for regulators and water suppliers. (). https://books.byui.edu/-qkTf

WHO. (2022). Guidelines for drinking-water quality. ().WHO. https://books.byui.edu/-UeaE