1.5: Water Quality
One of the most important responsibilities of a water utility is to provide SAFE drinking water. “Safe” can be a confusing word for water utility customers. At times the safety of drinking water is confused with its aesthetic qualities such as taste, odor, and color. Sure, no one wants to drink water that is discolored, has an odor, or tastes bad. However, most of the time the water is safe to drink regardless of how it looks, tastes, and smells. Now, this doesn’t mean that water utilities are supplying customers with aesthetically unpleasing water. It simply means that often the safety of the water has little to do with its aesthetic quality. This is why there are both PRIMARY and SECONDARY drinking water regulations. Primary standards deal with health-related issues while secondary standards focus on aesthetic qualities of the water supply. Although water utilities strive to supply the best water possible, there are times when the water might be unpleasant from aesthetic characteristics. This chapter will discuss both primary and secondary water quality regulations, providing examples of both, as well as a discussion of various job opportunities within this discipline of the water utility industry.
Almost everyone is concerned with the quality of their water. It is typically the top complaint from customers, with the exception of high water bills. Since tap water is usually colorless, odorless, and, for the most part, tasteless, as soon as something changes, customers want to know why. Water quality is also a top concern of water professionals. Water quality professionals are responsible for the treatment, disinfection, testing, and compliance of the water served to their customers. Every year water utilities collect thousands of water samples and have them analyzed by laboratories to ensure compliance with water quality regulations. In addition to collecting samples, water utility operators conduct preventive maintenance, routinely inspect facilities, and respond to customer complaints to prevent and/or correct any water quality problems.
Water Quality Regulations
Current drinking water regulations are very complex and include many different requirements. This following text is a brief historical overview. President Gerald Ford signed the Safe Drinking Water Act (SDWA) in 1974 under growing pressure from newspaper articles, documentaries, and the general public’s skepticism that drinking water might not be safe. The Environmental Protection Agency (EPA) conducted a national reconnaissance study to assess the concentrations, sources, and potential danger of certain contaminants in municipal drinking water supplies. In 1977, the national safe drinking water standards went into effect across the country. These standards included microbiological contaminants, ten (10) inorganic chemicals, six (6) organic pesticides, turbidity (or cloudiness), and radiological contamination. Among other things, the regulations also included a provision for the States to assume primary enforcement responsibility.
Since the enactment of the Federal Safe Drinking Water Act, there have been two (2) amendments. In 1986, the first amendment was passed. Some of the new requirements with this amendment increased the number of regulated contaminants, required certain filtration processes for surface water supplies, added disinfection requirements for some groundwater systems, and prohibited the use of lead solders, flux, and pipes in public water systems. Ten (10) years later the 1996 amendment was passed. This added a provision in the SDWA referred to as the Unregulated Contaminant Monitoring Rule (UCMR). The UCMR requires the EPA to provide a list of potential contaminants every five (5) years to water utilities so that their drinking water supplies can be analyzed. The EPA will then use this data to prepare future water quality standards. The amendment also created distribution and treatment operator certification requirements and a funding system for states needing financial help to comply with drinking water quality regulations. This funding is referred to as the Safe Drinking Water Revolving Loan Fund.
It is important to note that although there are federal drinking water regulations, many states have their own drinking water standards. In California, the regulatory agency is the Division of Drinking Water (DDW) under the State Water Resources Control Board (SWRCB). The DDW is responsible for enforcing the California Safe Drinking Water Act (CSDWA). Many states create their own regulatory agencies to help enforce the Safe Drinking Water Act.
Drinking water quality standards can be broken into two main categories: Primary Drinking Water Standards and Secondary Drinking Water Standards. Each set of standards has a list of contaminants that must be monitored by municipal water utilities and they must be below levels considered safe. These safe levels are referred to in the regulations as Maximum Contaminant Levels (MCL). Each constituent has a separate MCL that cannot be exceeded in the water supply or else some action must be taken. An action can be as stringent as taking the source of supply (i.e., groundwater well) immediately out of service. Or it may increase the amount of sampling requirements for a particular constituent. Exceeding an MCL may also require some type of notification to customers. The goal is to protect the public from unsafe levels of potential contaminants in water supplies.
Drinking water quality regulations are not the only water quality regulations water utilities must comply with. There are many water quality regulations protecting the environment. These regulations are part of the Clean Water Act (CWA). The CWA regulates and permits the sampling and monitoring of discharges to “navigable waters of the United States.” Navigable waters are defined by the US Army Corps of Engineers as waters that are subjected to the ebb and flow of tide, and those inland waters that are presently used, or have been used in the past or may be susceptible to use in interstate or foreign commerce. This definition can be interpreted by water utility operators as any body of water wet or dry that discharges can flow into. Common water utility discharges include, but are not limited to flows from:
- Fire hydrant and dead-end flushing
- Water main flushing
- Meter testing
- Water leaks
- Storage tank overflows
- Water sample collection
Although water utilities are required to discharge water for a number of these activities, they must still comply with the CWA and the various State and Local regulatory agencies responsible for implementing the requirements set forth in the CWA. Much of the requirements involve preventing chlorinated water from entering a water body or preventing debris from gutters and storm drains being washed into a water body.
Primary Drinking Water Standards
Primary Drinking Water Standards are for contaminants that pose a health threat when detected in water supplies above an MCL. In order to establish an MCL, the EPA will take into consideration several different factors. They will examine the prevalence and exposure of the contaminant in the environment and in water specifically. A contaminant that isn’t found in water supplies often would find a place low on the EPA priority list. However, a contaminant that is widespread would be at the top of the list. The EPA also looks at health effects. If it is wide spread contaminant but has little to no known health effects to humans then an MCL would not be very probable. However, if the contaminant is toxic or a known carcinogen then an MCL would be very likely. Another consideration is in regards to the analytical methodology. There has to be a statistically reproducible laboratory analytical method in order for the EPA to consider an MCL. If a laboratory cannot detect the contaminant readily and statistically accurate, then having an MCL would be very difficult. Lastly, an economic evaluation is completed. Typically the cost benefit analysis looks at all the previously reviewed material.
Millions of dollars a year are spent by water utilities in efforts to comply with Primary Drinking Water Standards. It is one of the most important responsibilities of water professionals. There are a host of treatment technologies that are used to inactivate or remove contaminants from water. Thousands of samples are collected and analyzed to determine the level of each contaminant. Reports are prepared and filed with public health agencies to demonstrate compliance with the regulations.
Primary Drinking Water Standards are commonly broken up into four (4) main categories:
- Bacteriological
- Inorganic Chemical
- Organic Chemical
- Radiological Compounds
There are multiple constituents within each broad category and it is the utility’s responsibility (with the assistance from the regulatory agencies) to understand the requirements for complying with these contaminants. Below is a brief description of each category, the predominant health effect associated with each, and various treatment methods.
Bacteriological
This group consists of not only bacteriological contamination, but also viruses, protozoa and various other microorganisms that pose a health threat. Most of the health effects associated with microbiological contamination in water are gastrointestinal. Symptoms include vomiting, diarrhea, headache, fever, etc. Many of the symptoms are similar to influenza. However, to various sub-populations, for example the very young or old or people with compromised immune systems, the health effects can be deadly.
Because of the vast number of microorganisms and the difficulty and cost of trying to analyze all of them, an indicator organism group is used for analysis. This group is known as the total coliform group. Coliforms are a group of bacteria that indicate the presence or absence of disease causing microorganisms. The Total Coliform Rule (TCR) is a set of regulations that cover this wide range of contaminants.
Although there are various treatment techniques for the removal and inactivation of microbiological contamination, disinfection is the most common method. Drinking water treatment facilities and distribution systems both use disinfectant chemicals (primarily chlorine) for maintaining the health and safety of drinking water from microorganisms.
Inorganic Chemicals
There are many different chemicals found in drinking water supplies that fall under this broad category. Fortunately most of them are naturally occurring and are considered safe. For example, minerals such as calcium and magnesium are commonly found in drinking water supplies. Although these may pose aesthetic problems for consumers (discussed later in this chapter), they pose no health effects. However, contaminants such as nitrate, arsenic, and chromium can also be found as naturally occurring elements in drinking water and these can pose health problems if ingested at levels above the MCL. In addition to being found naturally in the environment, these and many others are the result of some type of contamination.
- Nitrate – The primary source of nitrate contamination is from some type of fecal contamination. Agricultural farms and leaking septic systems both contribute to nitrate contamination. The main health effect is related to infants six (6) months and younger. If nitrate is ingested at levels above the MCL by this sub-population, a condition known as metheglobinemia (Blue Baby Syndrome) can occur. This results in suffocation when nitrogen displaces oxygen in the bloodstream.
- Arsenic – Arsenic has been used as a wood preservative resulting in contamination and is also naturally occurring. The primary health effect associated with drinking water containing arsenic at levels above the MCL are cancer-related.
- Chromium – This chemical got its spotlight from the movie Erin Brockovich. An oxidized form of chromium known as “Chrome6” or hexavalent chromium was brought to everyone’s attention when Pacific Gas and Electronic was accused of contaminating the groundwater supply in Hinkley, California. This contaminant also causes cancer-related health effects.
Inorganic chemicals are not commonly found in drinking water supplies above their respective MCL. However, if they are, there are several treatment techniques that can remove these and many other contaminants from the water supply, ion exchange being one of the most common.
Organic Chemicals
The most commonly found organic chemicals found in drinking water supplies fall under the category of VOCs. VOC stands for volatile organic compound and are present in drinking water typically from the result of some type of contamination. Some of the more common VOCs found in drinking water include:
- Trichloroethylene (TCE)
- Tetrachloroethylene (PCE)
- Methyl Tertiary Butyl Ether (MTBE)
These chemicals come from various sources including degreasing agents, dry cleaners, and fuel additives respectively. These are considered “volatile” because of their propensity to evaporate or sublimate from the liquid or solid form of the compound and enter the surrounding atmosphere. Therefore, one of the more common treatment techniques to remove VOCs from drinking water is granular activated carbon in combination with packed air towers. The primary health effect from drinking water containing VOCs at levels above the MCL is cancer.
Radiological Compounds
The primary source of radiological compounds in drinking water is from naturally occurring sources. Geologic formations can contain uranium, radium, strontium and other radiological compounds. In rare cases, radiological contamination can result from a nuclear facility accident. However, this is not very common. As with many drinking water contaminants the primary health effect is cancer-related. Common treatment for radionuclides is ion exchange.
In addition to the treatment techniques previously mentioned, blending is a type of “treatment” technique that DDW may approve. However, blending is typically only approved for contaminants that do not pose an acute (immediate) health risk. The previous examples are not a complete list of potential contaminants in drinking water, nor is the information provided an exhaustive explanation. It is a glimpse into drinking water quality providing the reader a background overview.
Secondary Drinking Water Standards
Although Primary Drinking Water Standards are the most important regulations for water professionals, aesthetic quality is still a significant challenge and focus of drinking water providers. Making sure water is safe to drink is critical but if customers do not like the taste, odor, or color of the water they are likely to think that the water is unsafe and not fit for cooking and drinking. Therefore, it is important for water utilities to respond and take seriously all customer complaints, have a good preventive maintenance program, collect samples routinely and comply with all regulatory requirements. However, even the most diligent utilities can experience aesthetic water quality problems. Some aesthetic quality problems can be addressed by routine flushing and preventive maintenance programs, but some are the result of certain naturally occurring conditions and can only be removed through treatment and/or blending.
With varying sources of supply, comes varying water quality. Aquifer formations made up of limestone would tend to have higher levels of calcium, while other geologic formations might contribute other minerals such as magnesium, sodium, and potassium to name a few. Therefore, the quality of water in Los Angeles can be completely different than the water quality in Phoenix. However, in the United States all water must meet the minimum federal and state drinking water standards.
Common Aesthetic Issues with Drinking Water
Although the United States has some of the safest drinking water supplies in the world, sometimes little effort is focused on the aesthetic qualities. A crystal clear glass of water may not be safe to drink because it can have harmful tasteless and colorless contaminants in it. At the same time, discolored water with a bad smell and taste can be perfectly safe to drink. Everyone wants safe water to drink but it is usually the aesthetic qualities that determine if we will drink the water. Many times when people are asked why they drink bottled water instead of tap water, their answer is usually “because it tastes” better.
So why does some water look, taste, and smell bad? There are various things that can cause aesthetic issues with drinking water. The following scenarios provide just a few common issues facing water utilities. Please note that each scenario only reflects typical responses to common problems. They are meant as examples only.
- Scenario 1 - A customer calls their local utility complaining of a slight yellow color to the water. What can cause this discoloration? What should the utility tell the customer? As mentioned previously, all water quality complaints should be treated with concern and taken seriously. A common first response from a water quality professional might be, “Is the discoloration coming from all the faucets in the home?” This simple question will help determine if the problem is coming from the customer’s internal plumbing system or if it is coming from the water being served by the utility. If the discoloration is coming from all faucets, then the next step would be to check the water coming into the home. Sometimes the utility will send someone out to investigate, while other times the homeowner can be asked to flow the water at the front hose bib to check for discoloration. Usually the answer from the customer is the discoloration is only coming from a certain faucet or area in the home. A common source of the discoloration is from older galvanized internal plumbing systems. Sometimes a bathtub or sink is not used very often and iron from the internal plumbing system can leach out and cause a brown/yellow discoloration. A common suggestion to the homeowner would be to run the faucet for a while until the discoloration clears up.
- Scenario 2 - A customer calls complaining of cloudy water. Cloudiness or “milky” looking tap water is commonly entrapped air in the water. A test that water quality professionals ask the customer to try is to fill up a clear glass and set it on the counter. If it is air then the cloudiness will begin to clear from the bottom of the glass up. This is because the air bubbles will rise into the atmosphere.
- Scenario 3 - Sometimes customers will call and complain about odors. Customers will often call saying their water smells like a “pool.” Chances are something has changed in the distribution system or with the disinfection process. Drinking water is commonly disinfected with chlorine or chloramines. The switch from one to the other can cause “pool” chlorine type of orders. Or if water usage demands in the system have changed these same odors can be present for a short period of time.
No matter what the customer complaint is, all water professionals need to be honest, provide specific detail and help, and if they are ever uncertain of the solution to the customer’s concern, tell them they will need to investigate the issue and will provide them with a response as soon as possible.
As you can see, drinking water quality regulatory compliance is a complex and detailed area of the drinking water industry. However, regulations are readily available and government regulators are typically very helpful and responsive to questions from utilities. Water professionals and regulators alike should have the same goal of providing the public with a safe and reliable supply of drinking water.