Advice On A Troublesome Water Line Leak

Last year, my water bill when up about thirty dollars. Off and on all year my bill has fluctuated between near normal and thirty dollars higher.     Consumption averages about 7500. Here is a list of last years:

Dec 09    12100

Jan 10    11600

Feb       9900

Mar       6800

Apr       6800

May       8500

Jun       6400

Jul       6400

Aug       11100

Sep       5900

Oct       7700

Nov       9900

Dec       16000

Jan       15300

Each month pretty much had the same normal water usage for our family. We live on a farm and our water line is about 600 ft from the mainline. I shut off the main valve at our home and check the water leak indicator (small triangle) on the meter. It did not move. However after about 5 minutes is moved suddenly, but smoothy from the 5 o clock position to the 7 o clock position. So I recorded the following:

6 mins link indicator moved from 7 o clock to 8:30

17 mins ”                  “from 8:30 to 9:00

5 mins ”                 ” from 9:00 to 10:00

8 mins ”                 ” from 10:00 to 12:00

8 mins 15 secs ”          ” from 12:00 to 1:30

There was not continuous movement with the leak indicator, just smooth small increments after extended periods. This line does go to a horse waterer at our barn, which is not leaking. It also goes through our creek in a duck pipe. I sure would appreciate any comments or suggestions. Thanks