Several Factors Play Role in Leak Detection Plans

Leak detection: Should I do it myself or contract it out? Or, do I need leak detection at all? These are questions faced by every water department in the worlds developed countries, from the smallest village to the largest city. The first question that must be answered is: "Do I need leak detection?" Leak detection means different things to different water departments. There are a few approaches that are common:

1. Only fix the leaks when they surface or they have potential for damage.

2. Periodically (once every year, once every 5 years, etc.) contract with a leak detection services company for a "water leak survey" or "leak audit."

3. Do your own occasional water leak surveys and your own leak pinpointing with a sonic leak detector ($1000 to $4000 investment). Bring in the leak detection services company for only the difficult leaks.

4. Engage in an active leak detection program including your own employees performing water leak surveys and leak pinpointing every day, or at least regularly.

These four approaches range from "low investment, little concern" to "high investment, serious issue." The right approach for each water department depends upon the seriousness of the leak problem and on the availability of resources including personnel, trucks, and money.

The American Water Works Association (AWWA) publication No. M-36, titled "Water Audit and Leak Detection" provides guidance to every water department in assessing the problem and developing a leak detection program. The distribution system "flow balance," where the average pumping flow rates and average metered consumption are calculated, provides a valuable piece of information called "the unaccounted for" water loss. The current AWWA guideline is that any water department with more than 10 percent "unaccounted for" water loss should investigate whether there is a leakage problem.

The answer for every water department to the question "Do I need leak detection?" lies in the "unaccounted for" water loss and in the answers to these two simpler questions:

1. Do you have a lot of leaks every year?

2. When you do have leaks, are they big ones?

Staff vs. Contractor

Whether to conduct leak detection in-house or contract with a leak detection company is a problem faced by each water department. And it totally depends upon the extent of the leak problem.

Staff vs. Contractor

The AWWAs M-36 publication contains a table of the costs for water losses for different size leaks. Water leaking through a round hole 0.20 inches in size would amount to about 10,655 gallons per day (GPD) and an annual cost of $1,945. But a larger leak, 1 inch long by one-fourth inch wide would amount to 63,504 GPD and $11,589 annually. Obviously, 5 or 10 half-inch leaks in a system can cost a city $60,000 to $120,000 each year.

Staff vs. Contractor

Leak detection services companies can offer a variety of services to water departments at a variety of costs. Contractor services start from "Listen Only" surveys at all hydrants and main valves. They cost approximately $100-$200 per mile or $400-$600 per day. Pinpointing leaks with correlator services raises costs to $150-$300 per mile or $600-$1200 per day. Correlator surveys on all lines and pinpointing leaks with a correlator can run as much as $350 per mile or $1500 per day. Emergency response for pinpointing a single leak can run anywhere from $400 to $1500 per leak.

Staff vs. Contractor

The range of these costs is wide due to a variety of factors. There are large variations in the service companies costs for travel, wages, and other expenses. Some systems are more difficult than others.

Staff vs. Contractor

Also, it is much more efficient to do a "listen survey and pinpoint with a correlator" than it is to do a correlator survey over all lines.