Commercial WATER Big, Bad Limescale

The detrimental effects of & scale on plumbing & water treatment equipment

By susan white

imescale caused by hard water can wreak havoc on any type of appliance, system, pipe or valve that water runs through. Due to drought in various parts of the U.S., hard water is becoming Lmore of a nuisance because of constant changes in the water table and groundwater quality. The challenges facing any business involved with maintaining water distribution systems today are extreme. Yearly maintenance and repair costs to water systems add up to many millions of dollars in certain areas of the U.S., and groundwater is only getting harder. According to the U.S. Geological Survey, pat- terns of hardness vary across the U.S. Water hardness is based on major chemistry concen- trations, which are relatively stable in groundwater and generally do not change over time. The softest water is found in parts of New England, the South Atlantic/Gulf states, the Pacific Northwest and Hawaii. Moderately hard water is An extreme example of the effects hard water can have on pipe common in rivers in Alaska and Tennessee, the Great Lakes region and the Pacific Northwest. Hard damage boilers, cooling towers, water heaters and using or exposed to the systems. and very hard water is found in some streams in other water-handling equipment. ASHRAE identifies the conditions in a building’s most of the country. The hardest water was mea- High levels of hard water such as Ca2+ water system that make it less likely for Legionella sured in streams in Texas, New Mexico, Kansas, and Mg2+ can cause scaly deposits in plumbing, to grow and spread, and recommends mainte- Arizona and California. appliances and boilers. These two ions also nance procedures and hazard controls to stop the combine chemically with soap molecules, result- spread of the bacteria. The standards are aimed Damage & Disease ing in decreased cleansing action. According to at building/facility owners and managers, but Wikipedia defines limescale as “the hard, off- the American Water Works Assn., ideal-quality they also are useful to professionals involved in white, chalky deposit found in kettles, hot water water should not contain more than 80 mg/L designing water systems, to ensure their practices

boilers and the inside of inadequately maintained of total hardness as CaCO3. High levels of total are adequate to prevent Legionella exposure. hot water central heating systems.” The article hardness alone, however, are not considered a The degree of hardness standard as estab- noted that limescale often is found on the inner health concern. lished by the American Society of Agricultural surface of old pipe and other surfaces that have A report by the Salt Institute in October 2013 Engineers (S-339) and the Water Quality Assn. been subjected to hard water. Limescale is dam- linked research of Legionnaires’ disease to (WQA) is displayed in Table 1. aging to plumbing components and appliances, lime-scale deposits. The vast majority of cases According to WQA, the three basic categories and can be difficult to remove. of legionellosis are the result of exposure to for remediating hard water and limescale are: Wikipedia defines hard water as “water that Legionella through a water system. Any place • Chemical softening: lime softening, hot and has high mineral content ... [It] is formed when moisture can build up, such as hot tubs, air con- cold; lime-soda softening; water percolates through deposits of - and ditioning systems, hot water tanks or plumbing • Membrane separation softening: -containing minerals such as , systems, can cause bacteria such as Legionella nanofiltration; and chalk and dolomite.” The article pointed out that, to grow. Limescale deposits in the water system • Cation exchange softening: inorganic, carbo- although hard water is not a health hazard, it can allow bacteria to grow and potentially infect those naceous or organic base exchangers.

SUMMER 2015 Commercial WATER CW7 Commercial WATER

Traditional Softening Systems Table 1. Degree of Hardness Standard Levels For traditional limescale prevention, the technol- Degree of Hardness Grains Per Gallon (gpg) ppm (or mg/L) ogy of choice always has been ion exchange water Soft <1.0 <17.0 softening systems, especially when it comes to commercial water distribution systems. Softeners Slightly Hard 1.0-3.5 17.1-60 have come under scrutiny in the past 10 years due Moderately Hard 3.5-7.0 60-120 to the salt they discharge into the environment and Hard 7.0-10.5 120-180 the amount of water they waste; however, they still provide the best overall protection against corro- Very Hard >10.5 >180 sion from limescale. A large-scale study conducted by the Battelle Chemical Treatment Solutions education is key to any prevention technology. Now Memorial Institute and commissioned by the Chemical softening has long been a treatment of owned by AO Smith, it employs a system using Water Quality Research Foundation in 2009 found choice for hard water due to its cost-effectiveness. template-assisted crystallization (TAC), a catalytic that “adding a water softener helps water heaters One of the oldest treatment options—phosphates— media process that transforms minerals into harm- and major appliances operate as efficiently as has been shown to offer continued protection from less, inactive microscopic crystal particles that possible, while preventing clogs in showerheads, limescale buildup in water distribution systems. pass to the drain. It is a scale prevention device faucets and drains.” The study also found that According to the Phosphate Facts website, with proven third-party laboratory test data and water heaters could maintain their original factory “Experience has shown that polyphosphates not years of successful commercial, residential and efficiency ratings for as long as 15 years when only inhibit scale formation, but they can also help food service applications. AO Smith uses studio using softened water. With hard water, efficiency remove existing hard deposited carbonate or sul- online streaming and hands-on local training to was reduced by up to 48%. Hard water affected fate scale.” It describes how potable water pipe educate its customers on the need for protecting both electric water heaters, in which the heating that has been treated with polyphosphate over water heaters and boilers. elements could be damaged by scale, and tank- several months shows improvement slowly, as Media marketed under the brand names Next less water heaters, some of which failed after scale begins to disintegrate. As the scale softens, and Filtersorb SP also have had successful track only 1.6 years. the particles are deflocculated and can be carried records as alternatives, and claim Additionally, the Battelle study found that away through the pipe system. a spot in the realm of environmentally friendly showerheads performed better with softened The website also noted that “polyphosphates, products using TAC technology. water—with hard water, some showerheads’ alone or in combination with orthophosphates, can capacities were reduced by 75% in less than 18 effectively control corrosion on both ferrous and Other Scale Control Technologies months. Faucets also were negatively affected by non-ferrous metals and alloys. Polyphosphates are Other technologies tout scale control, such as hard water, with strainers clogging in days in some particularly effective as corrosion control agents magnetic, electromagnetic and electrostatic cases. A study conducted in 2013 concluded that at lower temperatures and at a pH of less than devices, but their efficacy remains unknown. water softeners virtually eliminate energy-wasting, 7.5. They have also been shown to be effective Magnetic treatment consists of passing hard water service life-shortening scale accumulation on gas in brackish water (greater or equal to 2,000 ppm through a magnetic field. Promoters of magnetic and electric water heaters. Another recent study sodium chloride, or NaCl) with corrosion reductions devices claim that this simple operation provides concluded that softeners set with appropriate salt of up to 90% being reported.” a scale control method, even for water with a high efficiency do not harm septic systems, and may For commercial water treatment, a commercial tendency for scaling. It also is often claimed that actually improve their effectiveness. polyphosphate system distributed by ScaleZERO magnetic exposure can inhibit corrosion. Despite these studies, many cities in California Systems employs a stainless steel vessel and have banned ion exchange softeners. This is several polyester pleated sediment filters from Priority for Prevention primarily due to the salt deposited into the United Filters Intl. Each filter contains several There are a multitude of technologies that can drain from the backwashing procedure. As a spheres composed of an NSF/ANSI Standard help protect water distribution systems and result, many water treatment dealers provide 61-approved hexapolyphosphate media called equipment from limescale. The fact remains that an exchange tank service and charge a monthly Siliphos, which is especially effective in water many commercial and facilities maintenance rental fee, eliminating any salt or backwashing heater systems due to its efficacy in hotter water. businesses today do not provide protection for issues. According to John Foley of Rayne Water This system is modular and can be configured for their equipment, resulting in many millions of dol- Systems, commercial water softeners remain a flow rates of more than 100 gal per minute with lars spent in unnecessary repair costs. This, too, top treatment option when a point-of-entry solu- inlet sizes up to 6 in., making it an ideal alterna- can provide opportunities for water treatment tion is needed. When valves, resin, configuration tive to traditional salt-based water softeners for distributors and dealers to evaluate and educate and proper installation are in alignment, softener both tankless water heaters and boiler systems. their customers. CW systems provide 30% to 40% higher efficiency. Simpler systems are offered by tankless water These factors play a critical role in the efficiency heater companies such as Takagi, which began Susan White is a freelance writer and and efficacy of ion exchange systems, but many marketing a residential treatment system in 2002, marketing consultant for various water systems today are not properly maintained. As a when tankless water heaters were first intro- treatment professionals. White can be reached result, they can pose an environmental impact. duced. The company always has maintained that at [email protected].

CW8 Commercial WATER SUMMER 2015