Bore water stains: why they appear and how to stop them coming back
Orange marks on paths, walls and basins are common where bore water is used. They are mostly cosmetic, but they point to what is in your water.
Orange, brown or black stains from bore water are usually caused by dissolved iron or manganese that turns solid when it meets air. The stain itself is mostly a cosmetic problem, but it tells you the water carries minerals you should not ignore. Fixing the marks and fixing the cause are two different jobs.
Start with where the stains appear, because that narrows down the cause quickly.
Stains outside: paths, walls and fences
Sprinklers fed from a bore are the classic culprit. Iron in the water dries on pavers, brick and render as orange streaks. The marks build up over time, and they often follow the spray pattern.
You can often cut the damage by changing where the sprinkler points. Aim it at the lawn or garden bed and away from walls, glass and the car. If you cannot move it, a sprinkler head with a lower, softer spray helps.
Stains inside: basins, toilets and the shower
If you use bore water indoors, expect rust-coloured rings in the toilet and on basins, and brown marks on white towels. That points to iron in water, or sometimes to corroded pipes. Compare it with brown water from the tap, since the causes overlap.
Black or dark grey marks can be manganese. The two often turn up together.
Cleaning stains safely
Use a product made for rust stains and follow the label. Test a small hidden patch first, because some cleaners etch stone, render or glass. Never mix cleaning products, and keep strong chemicals away from anything that goes in your mouth.
- Wear gloves and ventilate the room.
- Rinse well, and keep pets and children clear while it dries.
- Do not scrub hard on soft stone or render.
Cleaning only treats the symptom. If the water keeps running through, the stain will come back.
Dealing with the cause
The only reliable way to know what is in your bore water is a test from an accredited (NATA) laboratory. A hardness kit or a pool test strip will not tell you. Once you have a result, a water treatment specialist can recommend equipment sized to it, and that is rarely a one-size-fits-all product.
Be sceptical of any salesperson who quotes a fix before they have seen a lab result. If you only use your bore outdoors, redirecting the sprinklers may be all you need. For the basics of what a bore is and what you can use it for, see what bore water is.
Where the stain shows and what it suggests
The place and the colour narrow down the cause quickly. Use this table before you buy a cleaner.
| Where it shows | Colour | Likely cause | First move |
|---|---|---|---|
| Paths, pavers, brick and render | Orange streaks | Iron in sprinkler water drying on the surface | Move the sprinkler away from walls |
| Walls, glass and the car | Orange spray marks | Sprinkler overspray | Aim at the lawn or garden bed |
| Toilet and basins | Rust-coloured rings | Iron in the water, or sometimes corroded pipes | Compare with brown water from the tap |
| White towels and laundry | Brown marks | Iron in the water | Use a product made for rust stains and follow the label |
| Basins and fittings | Black or dark grey | Manganese, which often turns up with iron | Test a hidden patch before cleaning |
Cleaning treats the symptom only. If the water keeps running through, the stain will come back. Read brown water from the tap if the marks appear indoors.
Questions to ask a water treatment specialist
Treatment equipment is rarely one size fits all. Ask these before you agree to anything.
- What does my laboratory result say? A good specialist asks to see it. Be sceptical of anyone who quotes a fix without a lab result.
- What is the equipment sized to? The answer should match what the result shows, not a standard package.
- Is the work licensed? Anything connected to your plumbing is licensed work, and the rules differ in each state and territory.
- Do I need treatment at all? If you only use the bore outdoors, redirecting the sprinklers may be all you need.
- Does the equipment make the water safe to drink? A stain-free result says nothing about safety. Only an accredited NATA laboratory can tell you that.
- What does it need over time? Ask what servicing it needs, and who does it.
For the basics of what a bore is and what you can use it for, see what bore water is.
Frequently asked questions
What causes orange stains from bore water?
Usually dissolved iron, which turns solid and orange when it meets air. Manganese can leave black or dark brown marks.
Are bore water stains harmful?
The stains are mostly cosmetic, but they do not tell you whether the water is safe. Only an accredited (NATA) laboratory test can do that.
How do I stop sprinklers staining my walls?
Aim sprinklers away from walls, glass and paving, or lower the spray. Treating the water is the longer-term fix.
Can I treat bore water myself?
Cleaning stains is fine. Connecting treatment equipment to your plumbing is licensed work, so ask a specialist after getting a laboratory result.
Sources
What this page explains is based on these official sources. If you check one and it does not match what you read here, send it to us and the article gets corrected.
- NHMRC. Australian Drinking Water Guidelines
- Sydney Water. Water supply, wastewater and stormwater services