The short answer
The surest way to know if your irrigation water has iron is to test it. The strongest signs before a test are orange or brown stains that follow your sprinkler spray pattern and come back after cleaning. If your sprinklers run on a private well, iron is the usual cause. We test irrigation water for free.
Signs your irrigation water has iron
- Orange or brown bands on fences, walls, curbs and driveways right where the heads spray
- Staining that’s darkest near each head and fades between them
- Stains that come back weeks or months after cleaning, in the same places
- Orange residue around sprinkler heads, valve boxes or the well equipment
Why clear water can still stain
Iron in groundwater is usually dissolved, so well water can look perfectly clear coming out of the heads. It only turns orange after it’s sprayed into the air and dries on a surface, where the iron oxidizes. Clear water is not a sign that your water is iron-free.
Is your irrigation on a well?
Many Tampa Bay neighborhoods irrigate with city or county reclaimed water, and iron staining from reclaimed water is uncommon. Private shallow wells are the usual source. If you don’t know what your sprinklers run on, look for a well pump near the irrigation controller, check whether your utility bill includes reclaimed water, or ask us to check during a visit.
What the numbers mean
Iron is measured in milligrams per liter (mg/L), the same as parts per million. The U.S. Environmental Protection Agency’s secondary standard for iron in drinking water is 0.3 mg/L, set for aesthetic reasons including rusty color and staining (EPA). It isn’t a rule for irrigation wells, but it’s a useful reference: water above that level is the kind that leaves orange stains.
How fast staining builds depends on more than the number. How often and how long your sprinklers run, and how close the heads are to your surfaces, matter just as much.
What to do with the result
- Little or no iron: you likely just need the existing stains removed, and we’ll look for another source if they return.
- Iron present: removal plus an irrigation rust prevention system, set up around your watering days and times.
We test water across Tampa Bay, from Clearwater and St. Petersburg to Tampa and Wesley Chapel. See all service areas.