In many jurisdictions, persons working on septic systems are licensed to do so. I doubt that the irrigation guys have such a licence. Getting this work done by licenced personel protects you against liability.

In our area we had to get a septic permit from the county based on the design of the system. I don't know if there might be problems down the road if you tried to tell for the unpermitted changes. Also, I believe there is some caculation involved in the pipe length and direction that effects flow rates and discharge. That might be something to consider as well.

I was asking can I change the setting not the time just the direction of the sprinklers. I had the system serviced this am and he changed them, but one is not right--I watched him (not right over him) but it did not look difficult. I cant call him back out, then I would have to pay him another service call.

Same question system has been working fine now I have one head that goes 360 when discharging how do I adjust it again it's about 10 yrs old