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Steps in a Water Audit
OTHER PARTS OF THIS ARTICLEPt. 1: How Does a Water Audit Work?Pt. 2: This Page
Step 1: The Water Use Inventory.
It is important that facility executives develop an understanding of exactly how and where their facility uses water. To do this, an inventory of all water use points in the facility with flow rates must be developed.
Start with a walk through of the facility, identifying every point in which water is used. For items such as toilets and faucets, the inventory should include the item, its location and its flow rate. If the facility has low-flow fixtures or if flow restrictors have been installed, identify them on the inventory.
Don’t overlook building mechanical systems. Mechanical systems account for approximately 25 percent of the total water use in an average building. For example, cooling towers and boilers are large users of water. Both systems require that a certain quantity of water be bled off and replaced in order to control the level of solids suspended in the circulating water or steam. Check the blow down system for cooling towers and boilers to determine the rate at which make up water is being added.
Refrigeration units that use once-through cooling systems also can be very large users of water. The inventory should include the type of system installed, its location, its capacity, and the rate at which it uses water for cooling. In some cases, the owner’s manual will identify the water flow rate. However, it may be necessary to use a stopwatch and a bucket to determine the actual water flow rate.
Irrigation systems also can be a significant water user. The inventory should include the number of systems, the number of sprinkler heads attached to each system, the flow rate of the systems and types of controls installed. Note if each system is equipped with ground moisture sensors to prevent activation during or immediately following a rainfall.
In addition to identifying all water use points and flow rates, the inventory should identify if the water being used is hot or cold, or if it undergoes special filtering or treatment. Reducing water use in applications that use hot or treated water will produce savings that go beyond solely the cost of the water.
When completing the inventory, pay attention to any unexplained water flow. As piping systems are modified over the years, it is easy to lose track of what piping serves what equipment. Don’t be surprised to find water flowing from equipment that is no longer used or even installed.
Step 2: Metering.
Unfortunately, most facilities only have a single, master water meter. Readings from master meters will provide an indication of how a facility compares to other facilities, but it will not show where to look for areas where water use can be reduced, particularly if the facility is large or complex. Narrowing use down to possible areas where use can be reduced requires submetering.
Where and how submeters are installed depends to a great extent on the design of the water system serving the facility. Ideally, submeters would be installed on individual zones or floors of the facility. Equipment with large water use rates, such as cooling towers and process cooling equipment, would each have separate submeters.
Each meter should be read at least monthly. If there are suspicions that the readings for a particular meter are high, or if the readings for a meter suddenly increase, it will be necessary to read that meter more frequently; even on a daily or twice-daily basis. Meter readings taken while the facility is closed and processes are shut down is one way to narrow the search for leaks and losses. All meter readings should be logged and reviewed on a regular basis for unexplained changes.
Tracking water meter readings will provide a baseline of water use for the facility. Just as energy use for different types of facilities was tracked on a use-per-square-foot basis to allow comparison between similar facilities, so can water use. However, other measures than square footage will likely be more meaningful. For example, in hotels, use can be tracked on a per-occupied-room basis. For restaurants, it could be on a use per-meal-served basis. Office facilities may use a square-foot basis or per-building-occupant basis.
Again, the key to gaining useful information from submeters is to have the meters read on a regular basis, and as frequently as possible. Frequent readings help to quickly identify and locate leaks.
Step 3: Review Maintenance Practices.
If water conservation has not been a priority in the past, chances are no one individual or group has the overall responsibility for conserving water. And as with many things in the world of facility management, if no one individual has responsibility for an item, then it is not a priority for anyone. As a result, specific water use related problems may have been seen by a number of people but not really noticed or acted upon.
Preventive maintenance programs have long been recognized as effective tools for improving system performance while reducing overall operating costs. With water use historically being an ignored or low priority item, chances are few preventive maintenance steps have been put in place to specifically address water use. How often are restrooms checked for faucets that don’t fully shut off or flush valves that leak or stick on? Does anyone ever test once-through cooling systems to determine that they are operating at the proper flow rate? How often are cooling towers and boilers checked to see that the make-up water systems are operating properly?
When maintenance issues occur within the facility, there is a system established whereby building occupants can report the problem. Does that process include water-use related issues? Do building occupants even know that they can and should report instances of excessive water use or waste?
Finally, what mechanism is in place to review water using items that are being purchased for use within the facility? For example, refrigeration systems that use once-through water cooling are less expensive and easier to install than closed loop systems. Closed loop systems however, have minimal water requirements. Is there an established procedure that reviews equipment purchases that addresses the issue of water use?
Step 4: The Water Efficiency Plan.
Once information has been gathered on how water is being used in the facility, an action plan can be established for reducing water use. The plan should identify who will take responsibility for implementation. It should make certain that individual has the authority and support needed to implement the plan.
The plan should set specific water use reduction goals for the facility. Those goals must be measurable, achievable and realistic. The plan must also identify a mechanism for periodically reviewing the success of the program in meeting those goals.
The water audit should have identified a number of areas in which water savings can be achieved. The water efficiency plan should set the priorities for implementation based on costs, benefits and available manpower.
Reducing water use in a facility is a win-win situation. Using less water means lower utility costs. It also means reduced chemical treatment costs in systems such as boilers and cooling towers. Finding and eliminating long-standing leaks can create a better work environment for building occupants, as well as reduce damage to building components.
Reducing water use can also enhance the public image of a facility. Facility executives should publicize the program’s successes and give credit to those involved. Even something as simple as installing moisture sensors on an irrigation system can improve the facility’s image. Consider how many times you have seen an irrigation system operating in the rain. What impression of the facility did it leave you with?
James Piper, PhD, PE, is a writer and consultant who has more than 25 years of experience in facilities management. He is a contributing editor for Building Operating Management
Steps in a Water Audit