I bought a replacement head to one of my sprinklers at Ace Hardware in Southern Trace shopping center. It is just the small head type that does NOT pop up, it just is screwed onto the post that sits over some plants. After being away from TV
for a week, I noticed a large hole dug out in my mulch and the mulch had moved onto my sidewalk. I did not think too much about it, I just covered it up again. I couple of days later it was the same thing. I have some gutters above this area so I checked to see if they were clogged and dumping water down onto this area. They were not clogged. I then happened to look at the sprinkler head that I had replaced and noticed that the whole center was gone. The only thing left was the threads. Every time the sprinkler system came on, the water would just poor out and flood this area. If this had not been in an area with mulch under it, I may have never noticed until my outside water bill sky rocketed.
I then went to Lowes for a replacement. You may want to periodically check your replacement , non pop up heads from Ace.
jeffy