How to Remove Rust Stains from a Bathtub — Toronto Home Guide

Rust stains in bathtubs are caused by iron in the water supply oxidizing on the tub surface, often from old pipes, a corroding tap fitting, or water with high iron content. Standard bathroom cleaners don't work on rust — you need an acid-based cleaner to dissolve the iron oxide.

Bar Keepers Friend (Most Effective)

1. Wet the stained area
2. Sprinkle Bar Keepers Friend powder directly onto the rust stain (or apply the liquid gel version)
3. Let it sit for 1–2 minutes — do not let it dry on the surface
4. Scrub with a soft cloth or non-scratch sponge in circular motions
5. Rinse thoroughly
6. Repeat if needed for heavy staining

Bar Keepers Friend contains oxalic acid, which dissolves rust effectively. It is safe on porcelain, ceramic, and fibreglass/acrylic when used as directed and not left to sit.

Lemon Juice and Salt (Gentler Alternative)

1. Sprinkle salt generously over the rust stain
2. Squeeze fresh lemon juice over the salt until it's saturated
3. Let it sit for 2–3 hours
4. Scrub and rinse

This works well for light staining on acrylic or fibreglass tubs where you want to avoid abrasive products.

What to Avoid

• Bleach — does not remove rust and can actually set the stain permanently
• Steel wool or abrasive scrubbing pads — scratches acrylic and fibreglass finishes, creating rough spots that attract more staining
• Leaving acidic cleaners on too long — can dull the finish on acrylic tubs; always rinse promptly

Preventing Rust Stains

• Rinse the tub after each use and dry the tap fittings — standing water accelerates rusting of metal fixtures
• Replace corroded tap washers or fittings — the rust source is usually a worn metal component
• A whole-home water filter reduces iron content if the issue is in the water supply itself