Did you test the irrigation system or are you assuming that it worked prior to purchase because the lawn was green?


Providing that you're 100% that the system was fine before you've got sediment in your sprinkler system or the bleach did damage or another fault. Are you using a timer to trigger each circuit? If yes, manually open it at the valve. Is there a vacuum breaker installed on the irrigation system? Have you pulled the screens in a sprinkler to check for sediment? Have you ran the system long enough to allow a broken pipe to become evident?

A broken pipe underground due to something like a moving truck would be my blind guess based on the information I have.