I have Rain Bird impact sprinklers and in ground rotary sprinklers that have been in service for 18 years running on lake water and they are still going strong! These brass impact sprinklers work great and are hard to kill.  I run my sprinkler pump at 30-40 pounds and I get plenty of coverage.  My 18 year old impacts and my new ones look about the same and they work the same!  Thanks, Rain Bird.