I have a severe problem with rust stains appearing on the sidewalk in front of my house.
I've had the sprinkler system checked, & PVC piping was used with standard Rainbird heads. No other house on the block seems to have this problem. I can't figure out what is causing this problem... The HOA is getting ready to fine me for the rusted sidewalk in front, but I've had it pressure washed repeatedly, and scrubbed with vinegar & undiluted lemon juice. I have not used muratic acid yet, because I do not want to damage the sidewalk.