Water Safety and Efficiency in Hospitality Buildings

Back-of-house water systems can impact guest satisfaction throughout a facility
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Sponsored by Watts Water Technologies
By Peter J. Arsenault, FAIA, NCARB, LEED AP

Water Quality and Conditioning

We have already established the need and expectation of good quality water in hospitality facilities so let’s look at some ways to achieve that. Fundamentally, there are two approaches, namely filtration and treatment, and both may be needed in any given facility.

Water Filtration

Water that arrives at a facility can contain a wide range of particulate matter, such as suspended particles, bacteria, viruses, gases, and others contaminants. The primary purpose of a filter is to remove these contaminants from the water before it gets to the point of being consumed. For hospitality situations, that may be accomplished with a large, commercial water filtration system at the water point of entry so the entire water supply is filtered. Or it may be accomplished on a point-of-use basis for selected locations, such as food service and beverage stations. The most common technology in either case is to use a carbon and/or fibrous filter that traps the physical contaminants and removes them from the water stream. Such filters require regular changing and related maintenance, but they can be very effective at removing unwanted contaminants from drinking water.

For cases where salts or other dissolved ions are a particular concern in water, reverse-osmosis systems may be worth considering. Reverse osmosis (RO) is a technology that is used to remove a large majority of contaminants from water, including dissolved solids such as salts, by pushing the water under pressure through a semipermeable membrane. Osmosis is a natural process that would normally induce the passage of clean water into heavier, salty water. Reversing the process through the use of a pump and pressure means the ionized, contaminated water is processed by the membrane and made clean. In the membrane, pure water is allowed to pass through the membrane material and exit as purified permeate water. Dissolved mineral salts are not allowed to pass through the membrane and become a concentrated reject stream that is sent to drain. Commercial RO systems are available that can provide multiple stages (two to six) of membrane processing to achieve 99 percent or better removal, with production rates ranging from 40 to 100 gallons per minute. Typically, these units are designed for floor-mount installations as a point-of-entry system for the full water supply or a dedicated portion of it.

Water filtration and treatment systems

Water filtration and treatment systems are available to address a wide range of concerns in sizes to suit a wide range of demands.

Water Treatment

Beyond filtration, there are other common water-quality issues that need to be addressed in hospitality settings. One of the first is the relative “hardness” of the water. Hardness is caused when compounds such as calcium, magnesium, and a variety of other metals are present in water, which is an excellent solvent and readily dissolves minerals it comes in contact with. As water moves through soil and rock, it dissolves very small amounts of minerals and holds them in solution. Since there is no health concern over hard water, the United States Environmental Protection Agency (EPA) does not issue standards for water hardness for public water supplies. However, hard water requires more soap and synthetic detergents for laundry and washing, and contributes to scaling in boilers and other water using equipment and appliances.

Water softeners are a commonly available technology to counteract the effect of minerals causing hardness in water. Typically, they use salts that react with the minerals to neutralize their effects. The degree of hardness will impact the amount of salts needed to achieve softening. Hardness is commonly measured in grains (64.8 milligrams) of mineral (commonly calcium carbonate) per gallon of water. Soft water is classified as having 1.0 grains or less of hardness. Between 1.0 and 7.0 grains, water is considered slightly or moderately hard. Hard water is defined as anything above 7.0 grains, with anything over 10.5 grains considered very hard. Salts used in water-softening systems have rated capacities for addressing hardness based on the level and the number of gallons of water that pass through it. Hence, the salts need to be changed periodically as their capacity for effectiveness is reached.

Other systems are available that seek specifically to address the problem of scale formation on internal and external plumbing surfaces. Over time, the minerals in hard water can attach to the metallic surfaces of a water system and start to build up. The resulting scale often becomes encrusted on the internal moving parts of valves, piping, and other components, effecting their intended purpose and potentially causing safety failures. In a boiler or hot water tank, heating elements can become coated with scale, reducing system efficiency and safety. In pipes and other components, it can restrict water flow and create potential breeding grounds for bacteria. In kitchen and laundry appliances, it can cause discoloration or pass some of the minerals on to things being cleaned, causing staining or discoloration in the process. While conventional water-softening systems can be used to address this, an alternative is to use a system which employs a template-assisted crystallization (TAC) process to prevent scale formation. This technology eliminates the need for salt, takes up less square footage than a water-softening system, and is generally regarded as much more economical with similar results. Anti-scale and water-softening systems may be installed at the point of entry to a building to treat both hot and cold water, or can be located directly before a water heater, boiler, or other water-using device that requires protection from the ill effects of hard water.

A final type of water treatment involves disinfection of the water to kill bacteria. While heating the water is good for legionella bacteria control, it may not be adequate for others. Some methods of disinfection involve the use of chemicals such as chlorine or the introduction of specific metal ions (i.e., copper) to prevent bacteria from growing. A simpler and highly effective technique against microbiological contamination in water is the use of a centralized ultraviolet (UV) disinfection system. Such systems are attractive not only because they can be very effective at killing microorganisms, such as legionella bacteria, but also because they are fairly simple to use and operate. Connected to a power source, they produce the UV light that is projected onto the incoming water without the need for any chemicals to be handled or added to the water. For large systems, they can be completely enclosed for safety to prevent any accidental UV exposure to people. They also typically have sensors indicating their use and performance levels and can be specified to operate efficiently by only turning on when there is actual water flow in the supply line. For hospitality facilities that are processing a large amount of water, such UV systems can be an economical means of protection.

Left: Stainless steel drainage diagram, right:a man draining water into a stainless steel drainage system

Stainless steel drainage products are more hygienic and longer lasting than alternative drainage products.

Drainage Systems

While much of what we have discussed so far is focused on the water supply, a significant portion of the water system in hospitality facilities is dedicated to water drainage. While most plumbing drainage systems follow some fairly standard design criteria, there are a few places that warrant some extra attention, particularly where hygiene is a priority. That could include things like bathroom and swimming pool showers as well as commercial kitchen drainage. In those cases, the use of stainless steel drains, fittings, and even piping have been shown to provide superior performance. Further, the nature of these stainless steel products often makes them quicker and easier to install than traditional materials.

For showers, standard, square, or round stainless steel drains can be incorporated into appropriately sloped floors. Increasingly, linear drains are popular, particularly for accessible or door-less showers such that the shower floor can be sloped in one direction toward the linear drain. In all of these cases, stainless steel provides superior performance, longevity, and low maintenance by being corrosion and chemical resistant. From a safety standpoint, they allow for shower floors that are flat and smooth to help protect against slips and falls. For hygiene, stainless steel is hard to beat since it provides an easy-to-clean surface that can lower bacteria growth and reduce the risk of infections.

In kitchens, stainless steel drains and piping provide similar benefits, particularly when linear trench drains are used under large cooking stations. In these cases, there are some particular characteristics to look for though. Gratings with open sides, rounded corners, and no cavities prevents waste and residue from depositing on the grating surface, thus providing easy and efficient floor cleaning. Infill of the frame and anchor tags improve hygiene and durability, minimizing the risk of frame distortion and flooring cracks maintaining a secure and durable bond to the floor. Channel geometry provides efficient water flow to the outlet area, keeping channels empty and clean, even during minimal water flow. Finally, rounded corners reduce the risk of joint deterioration and flooring cracks in resin flooring.

There are a few other ways that drainage systems can be considered in hospitality facilities. Rainwater harvesting can be undertaken using roof drainage piping connected to underground water storage tanks. The harvested rainwater can be used for landscaping or other non-potable needs. Greywater drainage from showers and kitchens can take advantage of the remaining heat in the water by running drain lines under outdoor walkways that are prone to ice and freezing, thus reducing the risk of outdoor slip-and-fall accidents. Other water diversion and reuse strategies like these can help reduce overall water demand, making the building more sustainable.

Backflow Prevention

Among the common elements in a water supply and drainage system, the use of backflow preventers is typical. Backflow systems are essentially a series of plumbing control valves that prevent the reverse flow of drainage water from entering into the potable water supply due to back-siphonage and/or backpressure. Some municipal water systems will require backflow systems, particularly on large water users such as hospitality facilities, since it is in the interest of public safety and health to do so. Therefore, including backflow preventers can be part of a control measure in a water management program in addition to a general best practice. Keep in mind that they don’t provide any treatment of the water, rather they simply help assure that the water is flowing in the proper direction to help maintain good water quality. When selecting backflow preventers, there are choices to consider. Stainless steel versions are available as basic or mid-tier products with some limited options. More robust and durable choices include ductile iron valves, some with epoxy-coated paint on the exterior, and designs for continuous or heavy usage.

 

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Originally published in Architectural Record

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