Rust stains in bathtubs are caused by one of two things: iron in the water supply that oxidizes when it contacts the tub surface, or metal objects (shaving cream cans, shampoo bottles with metal bases, steel wool) left on the tub surface. The stain is iron oxide — the same rust you'd see on metal — which has bonded to the enamel or acrylic surface. Standard bathroom cleaners don't remove it because they're not designed for oxidized metals. Here's what does work.
Identify Your Tub Surface First
The safe removal method depends on the tub material:
- Porcelain enamel — older cast iron or steel tubs with a porcelain coating. Harder surface. Can tolerate slightly more abrasive approaches.
- Acrylic or fibreglass — most modern tubs. Softer surface. Scratches easily. Requires non-abrasive methods.
Method 1: Salt and Lemon Juice (Mildest)
Effective for light rust stains on both porcelain and acrylic.
- Sprinkle table salt over the rust stain
- Squeeze fresh lemon juice over the salt to form a paste
- Allow to sit for 3–4 hours (or overnight for stubborn stains)
- Scrub gently with a soft cloth or non-scratch sponge
- Rinse thoroughly
The citric acid in the lemon juice dissolves the iron oxide; the salt provides mild mechanical action.
Method 2: Bar Keepers Friend (Most Effective)
Bar Keepers Friend (available at Canadian Tire, most grocery stores) contains oxalic acid, which dissolves iron oxide effectively. It works on both porcelain enamel and acrylic tubs when used correctly.
- Wet the stained area
- Sprinkle Bar Keepers Friend powder onto the stain, or apply the liquid/cream version
- Allow to dwell for 1 minute — do not leave longer, especially on acrylic
- Scrub gently with a damp soft cloth or non-scratch sponge — not a scrubbing pad on acrylic
- Rinse immediately and thoroughly
Do not use Bar Keepers Friend on natural stone (marble, travertine) — the acid will etch it.
Method 3: Commercial Rust Remover
Products like Zud or CLR (Calcium Lime Rust) are formulated specifically for rust on bathroom surfaces. Follow the product instructions carefully — dwell time matters and exceeding it can damage surface finishes.
Preventing Rust Stains
- Don't leave metal shaving cream cans, gel cans, or any metal-based containers on the tub surface — they're the most common cause of rust ring stains
- Use a shower caddy that keeps metal containers elevated above the tub rim or hanging
- If your water has high iron content (rust-coloured staining appears consistently): a whole-house water filter or iron filter is the only permanent solution — removing iron from the water before it reaches taps
Bathtub cleaning is part of Maidless's standard and deep cleaning services. Book a Toronto house cleaning — HST included.