Having the correct tools for the task at hand is an integral part in getting the job done, no matter what it is. Water quality monitoring is no different. Utilities need the right equipment to know what’s going on in their water system. Here, we’re going to go through some of the options utilities have when it comes to evaluating water quality monitoring indicators. The very best options are the ones that will fill all of your specific needs, so we’ve got a few different characteristics to go through so that you can find the exact right fit for your water system.
Before we can get into all that, though, we should make sure we’re all on the same page when it comes to water quality monitoring — what it means, what we’re looking for, and why each water quality indicator is important.
9 Common Water Quality Indicators
Before we jump into this section, it’s important to keep in mind that the nine water quality indicators on our list are only scratching the surface of what water quality monitoring can entail. Depending on your water system’s specific needs and a variety of other factors, you might need to monitor something that’s not on this list. We’ve narrowed our focus to some of the most common water quality indicators so that we can go more in-depth on each one, explaining the utility of each in some detail.
The main questions we aim to answer for each water quality indicator are as follows:
- What is it?
- Why is it important to measure it?
- How do you measure it?
With that information in hand, utilities can create more targeted water quality monitoring strategies and employ the right equipment to accomplish those goals.
Chlorine (free, combined, or total)
Adding chlorine is one of the most common forms of water treatment, When you add chlorine to a water supply, it eliminates harmful microbes and neutralizes contaminants that can cause health issues for consumers. Free chlorine (e.g. sodium hypochlorite) is the most widely used type of chlorine in the United States. Combined chlorine is created when adding ammonia to the free chlorine mixture stabilizing the chlorine residual for a longer time period. Total chlorine is a measure of both free can combined chlorine.
It’s important to select the appropriate chlorine sensor for the type of chlorine your system employs.
How clear or cloudy water is relates to its turbidity. The clearer the water, the less turbid it is. Turbidity measures the amount of light that material in the water scatters. Materials that can increase water’s turbidity include clay, silt, algae, and microscopic organisms, among others.
Turbidity is one of the water quality indicators that can still be useful even though it doesn’t point directly toward any specific microbiological or chemical contaminants. It essentially measures how efficient the filtering is. If the turbidity of finished, treated water is above a certain threshold, that can be a warning sign of filter deficiencies or too much debris in the water mains. It can also point toward other potential treatment problems that might introduce pathogens to the distribution system (e.g. biofilm).
This water quality indicator is measured by online turbidimeters, portable turbidimeters, or benchtop turbidimeters. The turbidity of the water can be determined quickly on site, making it one of the more convenient water quality monitoring methods.
Most people are at least passingly familiar with pH values. You probably studied it in science class at one point or another. So, as you likely already know, pH measures how acidic or basic a substance is, and it’s one of the most commonly used water quality indicators. It stands for potential of hydrogen. The scale goes from 0 to 14 — the lower the pH value, the more acidic the water is. A pH value of 7 is neutral.
The pH value is important to water quality monitoring because changes to it can indicate system contamination. If the regular pH value of a water system has been established and then experiences a decrease in observed pH level, that might be an indicator of undesired bacteria growing within the system.
What’s more, a water supply with a high pH level can taste bad, while a water supply with a low pH level can even degrade the pipes through which it runs. These are just a few of the reasons water quality monitoring often includes pH level as a main indicator. Utilities can monitor pH on-site, and they can get near-immediate results.
Perhaps this is one indicator that needs no explanation, but we’ll give a brief one anyway: The ability to carry an electrical current. Pure water actually has a very low level of conductivity, but sea water and other forms of water in which different materials are dissolved can have high conductivity.
Thus, this is one of the water quality indicators that has the potential to raise a red flag about how much dissolved material is in the water. This material might include chemicals (like chlorine), minerals, and even sewage leaks. A sudden change in conductivity can be a sign of a contamination event or a pathway breach within the water distribution system, which are both big problems that need to be addressed. Corrosion within the system can also cause the conductivity measurement to change.
Water conductivity also has a lot to do with the temperature of the water, which is one of the other water quality indicators we’ll discuss in a later section.
Water conductivity can be measured in the field or in the lab relatively quickly and cheaply. Professionals can use continuous online meters or portable instruments.
Water pressure is another indicator that needs little introduction, if any at all. We’re all familiar with showers that feel more like a trickle than a true stream of water, but changes in pressure can be signs of something much more than an unsatisfying shower. A reduction in pressure can be a possible indicator of a leak or even a water main break, among other bad signs. Plus, sharp changes in pressure can weaken the pipes over time, increasing the risk for cracks and leaks.
Comprehensive pressure monitoring throughout the entire system is important for those reasons. Utility managers need that depth of data in order to keep their systems in the best shape possible.
To know how much oxidizing potential water has, one has to measure its ORP. It’s difficult to get into this one without giving a full chemistry lesson, so we’ll keep it surface level. ORP stands for oxidation-reduction potential, and it gives utilities a better idea of how effective their sanitizing efforts are. The higher the ORP, the better. ORP can also be used to determine whether bio-film may be forming inside of water pipes (especially if using a combined/chloramines disinfectant) as ORP figures will normally drop.
This water quality indicator is multifaceted. Some water is artificially fluoridated in order to promote dental health. However, fluoride can also occur naturally in water, and consuming too much of it over long periods of time can cause health problems.
Fluoride in drinking water is typically measured either colorimetrically or potentiometrically.
Unlike some of the other water quality indicators on our list, everyone is already well familiar with temperature. It is an important feature for water quality monitoring because when water temperature climbs above 59 degrees Fahrenheit, it has a greater probability of developing harmful microorganisms and biofilms. Temperature also affects other water quality indicators, like dissolved oxygen content, which we cover in the next section.
Although a change in temperature doesn’t point to any one specific type of contaminant, it can still act as a valuable warning sign that something might be wrong within the system.
Measuring temperature is, as you might imagine, fairly simple. It can often be accounted for in an additional sensor added into a water quality monitoring device.
All kinds of water supplies need to be monitored for their dissolved oxygen component. In streams and lakes, the amount of dissolved oxygen is one of the factors that dictates how much aquatic life the water can support. But when we’re talking about water distribution systems, we’re mostly looking at dissolved oxygen in a different light.
One aspect that makes it important to measure is that it affects the taste of drinking water. Generally, water with a higher dissolved oxygen content tastes better than water with a lower dissolved oxygen content. However, utilities also don’t want to raise the amount of oxygen dissolved in the water as much as they possibly can. This is because too much dissolved oxygen can corrode pipes and damage the water system.
There are a few different ways to measure dissolved oxygen in a water supply. You can use electrochemical analysis, photochemical analysis, or chemical analysis. Whichever way you choose to do it, measuring the dissolved oxygen and making sure it stays within a safe range is vital.
Some Water Quality Monitoring Options
In the previous sections, we gave a few examples of the kinds of water quality monitoring devices professionals use to measure each indicator. Here, we’ll discuss those devices in more depth. They can measure different water quality indicators, but the differences run deeper than that. Let’s get into it.
Portable vs Permanent
Some monitors are fixed parts of a water distribution system, while others can be moved around. Take the Eclipse i-Series #9250i, for example, that we make here at Kupferle. It’s made to monitor pressure, and it attaches to any hydrant via a 2-1/2” NST connection. So, you can take it around to different points in a water distribution system and get pressure readings that way. If you want to monitor more than pressure Kupferle also manufactures the Eclipse i-Series #9700i-Solar that can hold up to eight different sensors like the ones listed about to monitor and flush water to keep residuals at safe levels.
However, if portability isn’t the main goal Kupferle manufactures a full line of permanent stations like the Eclipse i-Series #9800i-Genesis, for example. This permanent intelligent monitoring and flushing station stays in place, but it can also house up to eight different sensors. It will also automatically flush the system when residuals are below the set minimum level and powers itself directly from the water main using an incorporated water turbine and battery bank.
Different Power Sources
Water quality assessment requires power from somewhere. For an eco-friendly option, you might consider solar powered monitors like Kupferle’s Eclipse i-Series #9800i-WC-24LIS-A. As mentioned above, other monitors are constructed with a built-in water turbine to charge their batteries. And of course, there are options with regular lithium-ion batteries that charge by plugging into an outlet (portable) or running 120VAC line power to the station. Pay attention to the power source in the equipment you use to perform water quality tests to make sure they align with your needs and values.
Intelligent monitoring devices make it remarkably simple to access the water quality data. In most all instances, they can transmit the water quality data to your mobile device or SCADA. They can also generate water quality reports in the form of preformatted Excel worksheets and graphic displays. That makes it easy to track different water quality indicators.
Like we explained when we talked about the Eclipse #9800i-Genesis, some monitors also flush the system when they detect the levels are below programmed minimums. Instead of scheduling set times to flush aging water out of the distribution system, it’s done automatically and efficiently based on the chlorine residual and/or NTU. Not all monitors have that functionality, though, so it’s definitely something to watch out for if you’re interested in it.
Intelligent Monitoring and Flushing can save water, time, and money because of its precise nature. The water is only flushed when needed, and the exact amount of water to get those residuals back to the correct level is flushed. This can be a huge advantage.
Choose the right water quality monitoring equipment.
Here at Kupferle, we make several different types of water quality monitoring and flushing devices that meet the specifications we outlined in the previous section. Consider our different models of intelligent monitoring and flushing equipment. Many of them can incorporate up to eight different sensors that monitor for the water quality indicators we’ve listed here. That’s one piece of equipment that can handle many different water quality monitoring tasks.
Different water systems have different needs when it comes to water quality monitoring. As such, customizing your equipment to identify specific water quality indicators of concern is always a good call. Consider all of the indicators we’ve listed here as well as your options for equipment, and then choose the right water quality monitoring devices for your system.