We are required to keep our "Unaccounted for Water" below 10% of the water withdrawn on an annual basis.  Most of this water, totaling several millions of gallons, is lost through leaks in the distribution system.  Often times the leaks go undiscovered for months because they are in remote areas or do not surface due to very permeable soil conditions.  Each year we conduct a leak detection survey to try and locate as many leaks as possible and repair them.

We typically hire a vendor that has experience conducting these surveys because it is more of an art than a science.  The vendor uses a ground microphone and amplifier or computerized correlators to check the system for leak noise.  Water escaping from the pipe creates a vibration that can be heard and felt if the leak is severe enough.  The vendor's equipment allow them to find small leaks that can not be readily heard and their training helps them determine if the noise is a leak or someone using water.

A few factors will increase the importance of leak detection in the future.  As our water withdrawals decrease due to conservation efforts and mandatory water bans, the amount of leakage (if constant over time) will become a larger percentage of the water withdrawn.  This will make it more difficult to stay below the 10% threshold.  In addition, leakage will likely increase as the distribution system ages and is expanded.  System expansion creates more joints in the piping network and more opportunties for leaks to develop.

As leak detection equipment is improved and water becomes scacier it may become feasible to conduct the work throughout the year or permanently install leak detection sensors in the distribution system.  This is likely years, even decades, away but the trends are heading in that direction.