Whether seeping lazily from the clouds in the sky or forcing its way from behind man-made barriers, leaks are a fact of life.
While some people may be inclined to throw up their hands in disgust and discount water's natural talent as an escape artist, when you're in the business of selling water…every drop counts.
It's a fact that for most water distribution systems, a large percentage of water is lost somewhere between the treatment plant and the customer's faucet. While industry estimates place the amount of water that is lost, or unaccounted for, as high as 20-30 percent of what is produced, there is no question that some systems, especially older ones, may be losing even more.
While water loss could easily be ignored since the problem will generally disappear unnoticed into the earth, it is clearly a problem that must be faced.
In this issue of the Safe Drinking Water Trust eBulletin we’ll look at a few ways to determine just how much water (and profit) your system might be losing and how to plug the leaks.
Additional Resources
www.doh.wa.gov/ehp/dw/Word_Docs/Fact%20Sheet-Unaccounted.pdf [1]
Keeping the Profits From Drying Up
It's hard to envision any other industry where even a 30-percent loss would be tolerated…or even worse accepted.
Imagine, if you will, pulling up to the pump at your local gas station to fill your car's tank before a long trip only to see fuel forming a puddle at your feet because the hose leading to the storage tank resembles a rubbery piece of Swiss cheese.
Would you stand for it? Would you be willing to foot the bill for the fuel that didn't make it into your tank?
We think not. Instead, most consumers would be hopping mad.
The amount of leakage that can be tolerated in a distribution system is simply a matter of economics: the benefits of repair versus the labor that must be invested in locating and solving the problem. A reasonable target for most small water systems is to get the leakage rate below 15 percent of what is produced.
Looking beyond the sheer economic impact that distribution leaks pose, potential benefits of repairing leaks in your system are:
• Increased knowledge of your distribution system, which can be used to respond more quickly to emergencies and to set priorities for replacement or rehabilitation programs;
• More efficient use of existing supplies and potentially delaying expensive expansion projects;
• Improved environmental quality;
• Increased firefighting capability;
• Reduced property damage, reduced legal liability; and
• Reduced risk of contamination.
Additional Resources
www.epa.gov/owm/water-efficiency/wave0319/append_a.htm [2]
Dam Those Leaks.
While it may seem easier to just ignore a leaky waterline, it's a problem that won't go away—more than a nuisance, it is an economic menace.
One of the biggest concerns for any water system, especially one that has significant water loss due to unaccounted-for leakage, is the customer's health.
Any operator who isn't still "wet behind the ears" can tell you that it's simply impossible to maintain pipes that are constantly full of water and under pressure.
When line pressure drops, as it often will when large amounts of water are needed to fight a fire or when you are working on a line, water that was once leaking out of a system suddenly becomes water that is leaking in—potentially bringing contaminants along with it.
It's also important to consider your production cost for the leaking water, from the electricity that fuels the water pumps to the chemicals that treat it. If you are losing water—your physical and financial capacities are being affected.
Additional Resources
http://orcities.org/webdocs/wmcpguidebook.pdf [3]
Water: Tough to Hold.
The first step in assessing your system's water-leak woes is to determine just how much water is going "unaccounted for."
To do this, it's important to remember that your system must be metered.
Residential water meters are the cash registers for your system and must be installed and maintained in order to be effective—and so you know how much water your system is actually selling each month.
A "nightline" or "night-flow" audit is one way to estimate the amount of unaccounted-for water your system is generating. While it may involve a little overtime and loss of sleep, a night-flow audit will give you a good idea of how much water you are losing.
A benefit of this method is that it does not require universal residential metering (although this is highly recommended) and it can be performed on nearly any size system.
A night-flow audit is based on the notion that between the hours of 2 a.m. and 5 a.m. most of your customers will be tucked safely in their beds and not using a great deal of water. Based on this assumption, the majority of water flow can be attributed to leakage.
A more-comprehensive approach to determining how much water you are losing is a system water survey, or water audit. This can either be completed by your system's staff or by an outside firm.
A water audit is simply a management tool that measures the volume of water that enters a system and compares it to the volume of water that leaves the system. Depending on the size of your system, audits can be completed for the entire system, or you can break your system down into zones to help you determine where you are losing the most water.
It is a good idea to complete an audit annually so that you may operate at the highest possible level of efficiency.
Tip: Check out the Additional Resources link below for a more detailed look at how to conduct a night-flow audit of your system. Also, be sure to take a look at this month's Success section for a comprehensive water survey guide.
Additional Resources
www.nesc.wvu.edu/ndwc/pdf/OT/OTw93.pdf [4]
Getting the Drop on Leaks.
The best defense against leaks is to know your system and to read your water meters regularly.
Remember, in some cases the water only seems to be missing. Human errors (accounting or meter reading) or even inaccurate meters may give the impression that water is being lost. So it is important that you are familiar with your system so that water theft and other problems can be ruled out early in the game.
It's always a good idea to begin your leak-detection efforts by focusing on the portion of your distribution system with the greatest risk of problems, including those areas:
• With a history of excessive leak and break rates;
• Where leaks and breaks can result in the heaviest property damage;
• Where system pressure is high;
• Exposed to stray electric current and traffic vibration;
• Near stream crossings; and
• Where loads on pipe exceed design loads.
Once you have completed a water audit to determine the amount of water loss in your system, the next step is to find out exactly where the water is escaping.
The Soothing Sound of Water.
Most people remember the childhood story about the little Dutch boy who spotted a leak in the dike that protected his city and stuck his finger in the hole—filling the leak and saving the entire city.
If only things were that simple when it came to locating and fixing leaks in your water system.
Leak-detection equipment ranges from simple, inexpensive sonoscopes/stethoscopes to mid-priced acoustic amplifiers to high-dollar leak correlators—all of which require some degree of experience and training to obtain consistent results.
In areas that have been identified as having excessive leakage, the site of the leak can often be pinpointed using acoustic devices. These devices "listen" for the sound or vibrations created by water leaking from a pressurized system and are generally effective for finding leaks that occur at meters, valves and hydrants. This approach may utilize instruments such as listening rods, aquaphones, and ground microphones, which generally are easy to use and require only minimal training and experience.
Since water leaking from a pipe can often travel for several hundred feet before creating a noticeable damp spot or puddle, the acoustic listening devices could help keep your employees from digging up someone's entire yard just to find a small leak.
If purchasing an acoustic device (prices range from a few hundred to a few thousand dollars!) is too steep for your system's budget an affordable alternative is to hire an outside firm to help you pinpoint trouble areas.
Additional Resources
http://irc.nrc-cnrc.gc.ca/leak/leakfinder/ctu40e.pdf [5]
Detroit: Leak City?
City leaders in Detroit, MI will be the first to admit that water distribution leaks are a problem that just keeps adding up.
According to the Detroit Department of Water and Sewerage, the city's aging system is currently leaking more than 35 billion gallons of treated drinking water each year—costing the system roughly $23 million a year.
Most water systems don't even begin to produce as much water as Detroit is losing each year. To help you put the problem into perspective—that's enough water to fill a large, 4-foot-deep swimming pool roughly 1.6 million times, bathe every person in Metro Detroit in one shower per day for a year, or fill about one billion beer kegs.
The point to remember is: all systems will leak. Your job as board members, system employees, and consumers is to take every step necessary to ensure that your water system is operating in a safe and efficient manner.
So, why not take the time and effort now to complete a survey of your system's unaccounted-for water so that you can begin to take appropriate action before you find yourself having to stick a finger…and another finger…and another finger…then a toe…in your distribution system just to keep all the water from escaping.