Source Water Provides the Baseline

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"When you go to a doctor and they test your blood pressure, heart rate, temperature and weight, they're establishing a baseline that supports diagnosis and treatment. That's what you're doing when you test water at the tap," says Greg Garrett, director of technical services for Applied Materials Technologies and long-time member and instructor for the National Plasterers Council. "You're establishing a basis that will enable you determine how to adjust water chemistry for start-ups or ongoing maintenance. I cannot overstate how important that is."

In essence, without that baseline understanding of the constituents of source water, the pool professional is really making assumptions when he or she draws conclusions about water balance, proper sanitizing and controlling metals.

As anyone with life experience knows, assumptions are a gamble. They work fairly well in a certain percentage of cases. But in the cases where they don't work, costly surprises are the result.


According to Roy Vore, technology manager for BioLab and member of APSP's Recreational Water Quality Committee, assumptions about source water are both risky and common because many builders and service techs simply don't appreciate just how variable water conditions can be from place to place.

"Whether you're operating across state lines or even different water districts in the same city, you can have completely different conditions," he says. "You have to be aware of the potential variability you can face because it will dictate how you treat the water. If, for example, you're servicing accounts in an area with extremely soft water, with low calcium and total alkalinity, then you know you'll need a lot of calcium and alkalinity on your truck and that it's going to take time and visits to maintain balanced water. You might have accounts in another part of town where the exact opposite is true."

Even ahead of breaking out the test kit, Vore says the first step is to first know where the water is coming from. Specifically, if it's treated municipal water or water from a well.

"Well water may be a local well or a household well that's not treated. It might be close to the surface and full of all sorts of organics, metals and other minerals, or it can be from a deep well that doesn't have any organics. Municipal water is more reliable in terms of conforming to drinking water standards, but it also might not necessarily be balanced water. Before you even identify the variability, you need to find where the water for that particular pool is coming from because it points you in a direction."

Learning the water's origin might be as simple as asking the homeowner. Other times, it might involve doing research. As a rule, public utilities maintain and publish information about water sources, treatment methods and chemical levels. But as Vore points out, "Sometimes you have to ask."

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Mineral balance can vary tremendously depending on whether source water originates in a well or is treated in a municipal treatment system. If left unadjusted, water that is basic will form scale on surfaces, plumbing and equipment and even compromise sanitizer performance. Water that is acidic can damage cementitious materials and metal components.

"If you're going to maximize the longevity of the entire vessel, including the plumbing, you're always going to have to be concerned with balance," Vore says. "That's true for all types of pools. A vinyl liner, for example, might be somewhat less susceptible to scale or corrosion, but water balance is still going to be extremely important to the life of liner. Basically just about everything in a pool or spa lasts longer if the water is balanced."

Both Garrett and Vore have years of experience testing source water throughout the U.S. and both can share numerous accounts of source water that is surprisingly out of balance. Garrett, for example, recalls that the most aggressive water he's seen was in a water district in the Portland, Ore., area where the water at the tap had 6-to-8 ppm of calcium hardness and total alkalinity of 10 to 12 ppm.

"That water was so aggressive it's scary to think that some people were using it to fill pools and not making the necessary adjustment," he says. "That's an extreme example, but it's not unusual at all to find calcium at 50 ppm, for example. And it's important to understand that those levels not only change from place to place, but they can change dramatically over time."

In Garrett's hometown of Phoenix, he's seen tap water change from calcium hardness of 220 ppm or more to 50 ppm. "You cannot assume that it stays the same," he says, "because you never know when you'll get bit."

"The most aggressive water I've seen has been in southern Louisiana," Vore recalls. "It was extremely low in total alkalinity and calcium. It's basically like filling your pool with rainwater. When you're constantly refilling with that kind of water, you have to be aware the effort it's going to take to maintain balanced water."


Part of the challenge, Vore says, is that municipal water treatment facilities have a very different agenda compared to pool and spa operators. Because water delivery systems often include both concrete and metal plumbing, many districts deliberately keep water balance in a slightly scaling condition to essentially coat and protect their plumbing systems.

By the same token, some municipal treatment systems will alternatively run aggressive conditions to remove scale from their plumbing systems. Either way, it's up to the builder (during a start-up) or a service technician/pool operator (while maintaining the water) to routinely monitor balance at the tap and adjust accordingly.

"Public water treatment operates with a completely different philosophy and approach," Vore says. "It's very different than what we're trying to do in swimming pools. We don't want scale because we don't want to scale the inside the pool and the heat exchanger. The public water treatment will very often be trying to accomplish the exact opposite."

Based on Garrett's experience testing tap water, a practice that dates back to 2000 and has led him to hundreds of sites throughout the U.S. and elsewhere, he's come to believe that aggressive water, particularly water with extremely low calcium hardness readings, has increased in frequency.

"We're seeing extremely low levels in areas where you once had balanced water," he says. "In some cases, you have areas where people in the industry assume they have calcium coming in at 200 but when you test it, you find out it's below 50 ppm. That's a huge difference and if you're not aware of it, your pools can experience significant damage, whether it's plaster issues, or leaching tile grout or corroding metal components.

"I've seen extremely low calcium hardness throughout the U.S. including Portland, Seattle, Boise, Atlanta, and parts of Phoenix and Chicago, to name a few," he recalls. "If you monitor conditions in those areas, and everywhere else, and balance the water, you won't have problems. If you just assume the water's balanced at the tap and it's not, it's almost impossible to avoid the issues associated with aggressive water conditions."

Why exactly utilities alter their water chemistry is hard to determine. In some cases they change their own source water, which is common in times of drought. Or as mentioned above, they may deliberately change calcium levels to descale their delivery systems.

Because such shifts don't impact the safety of tap water (with the exception of extreme cases such as the lead contamination in Flint, Mich., where a shift in water balance corroded lead plumbing) utilities are not compelled to share those changes in treatment with the public. All the more reason that vigilance and routine testing at the tap is so important for pool and spa professionals.


Water balance can also impact sanitizer performance, largely because chlorine is less effective at elevated pH levels.

"The chemical composition of a water supply, including minerals, alkalinity, hardness, pH and other constituents can contribute to demand for halogen disinfectants," says Dave Purkiss, general manager, water and plumbing systems for NSF International. "For this reason, public water utilities are careful to monitor residual disinfectant concentrations in finished water. Having residual disinfectant is key to minimizing risks related to microbiological contamination of the water supply."

In order to maintain a disinfection residual in municipal water supplies, many utilities turn to the use of monochloramine, a disinfection by-product that contributes to chlorine demand in a swimming pool or spa. Burkis explains: "The U.S. EPA has established specific guidelines regarding the use of monochloramines (a type of chloramine) to disinfect drinking water, taking into account overall public health including disinfection efficacy, residual disinfectant concentrations and potential health impacts."

While the use of a DBP as a sanitizing agent may seem counterintuitive to pool and spa professionals, Vore explains that, again, it's simply an example of how water treatment utilities have a different agenda than people who maintain water chemistry for recreational bodies of water.

"You might be in a location where the water travels 20 miles from the treatment plant before it reaches your property," Vore explains. "Monochloramine is very slow acting but very stable, so it will maintain a residual while the water is moving through the system. If they used standard chlorine, there might be no residual when it gets to your tap."

The challenge to pool and spa professionals is that while monochloramine might be useful in assuring safe water for public consumption, it also will add to the chlorine demand in a pool or spa. "Again, knowing the treatment method and conditions used in municipal water treatment lets the servicer know what they're dealing with," Vore says. "In the pool and spa industry we're concerned with a quick kill, which is why we use standard chlorine, so it's a completely different mindset."

RELATED: Chloramines in Source Water

The possible harmful effects of ingesting DBP's in drinking water have been well documented and become the focus of significant public concern. Because, as Vore points out, pool and spa water is not by definition drinking water and is not directly consumed in large quantities, the issue is somewhat different for the pool and spa industry. Still, the increase in chlorine demand as well as issues associated with chloramines such as smell, eye irritation and respiratory problems means it remains good practice to control the level of byproducts in the water.


We'll leave this discussion with a reminder about third area of concern when it comes to source water: metals.
Metals cause stains and can discolor or cloud water. The most common metals impacting pools are copper and iron; others such as zinc, cobalt and manganese can also cause staining under certain conditions. They enter the pool by way of corrosion of metal components due to aggressive water chemistry (another reason water balance is so crucial) or via source water.

As is the case with mineral constituents or DBPs, contending with metals is not difficult, but you shouldn't assume they're not present in source water.

"It's those assumptions that get you into trouble," Garrett says. "I remember testing water in Torrance, Calif., where we had never seen metals, but we were getting reports of iron problems. I walked in the backyard of a pool that was having staining issues and immediately saw a huge brown stain coming out of the fill line. I tested for iron and sure enough, there was 3.3 ppm iron."

"That's just another reason why you shouldn't let complacency set in," he says. "No matter where you are or how familiar you think you are with the local water conditions, testing source water is imperative."


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