The water in your taps affects how your bathroom looks and how you clean it. That includes the sealant around the bath, shower and basin. Mr Mastic works across London, the South East and all of Scotland, which covers areas with hard water and areas with soft water. This guide explains what that means for sealant.
Hard water in the South East
Thames Water says most of the water in the South East of England is hard, because it passes through chalk and limestone, which add calcium and magnesium (Thames Water: hard water). Your own water company can tell you how hard your supply is. Southern Water, for example, has a postcode checker (Southern Water: how hard is your water).
When hard water dries, it leaves limescale. On sealant, that shows as a chalky white or grey crust along the bead, especially where water sits after a shower.
Soft water in Scotland
Scotland’s drinking water quality regulator says most drinking water in Scotland is classified as soft, because chalk and limestone are not common there (DWQR: water hardness). Scottish Water can tell you the typical hardness of your own supply.
Soft water leaves far less limescale. Soap lathers easily, so it is easy to use more than you need, and leftover soap film along the bead can be what feeds mould. Soft water doesn’t stop mould. Ventilation and wiping still matter.
How limescale affects sealant
- It looks dirty. A scaled bead looks grey and tired even when it is sound.
- It gives mould a foothold. A rough, scaly surface holds moisture and soap residue.
- Cleaning it can cause damage. Scrubbing scale off with abrasive pads scuffs the sealant.
Limescale doesn’t make sealant leak on its own, but a heavily scaled bead is often a neglected one.
Need it done properly? Mr Mastic covers the South East, London and Scotland, with a one-year guarantee on every job. Call or email for a quick quote.
Cleaning limescale off silicone
- Use a limescale remover that the label says is suitable for the surfaces around it, and follow the instructions.
- Apply it, leave it for the time stated, then wipe with a soft cloth. Don’t scour.
- Rinse thoroughly. Acidic descalers should not be left on sealant, metal fittings or natural stone.
- Never mix descalers with bleach-based products.
- Dry the joint afterwards.
The best defence is prevention. A quick squeegee or wipe after each shower stops scale building up.
When the bead needs replacing
If cleaning shows black mould inside the bead, cracks or edges lifting, the sealant needs replacing rather than more cleaning. A bathroom reseal removes all of the old sealant, cleans and treats the joint and lays new anti-fungal silicone. If the grout is also stained or cracked, regrouting at the same time leaves the whole area fresh.
For daily habits that help, see our aftercare tips.
Taps, screens and grout
Limescale doesn’t only collect on sealant. Shower screens, taps and grout lines scale up too, and cleaning them often splashes descaler onto the bead. Rinse the sealant whenever you descale nearby surfaces.
Grout in hard water areas can also hold scale and look grey. A gentle clean helps. Where it is cracked or deeply stained, regrouting may be the better answer.
Quick answers
Does a water softener help sealant?
A softener reduces limescale, so beads stay cleaner and need less scrubbing. Thames Water advises not to use softened water for drinking or cooking.
Is clear or white sealant better in hard water areas?
Scale shows on both. Dark colours show white scale most clearly.
Does soft water mean less mould?
No. Mould depends on moisture, warmth and residue. Ventilation and wiping matter wherever you live.
Will limescale make my sealant leak?
Not on its own. But a scaled bead is harder to keep clean, and hard scrubbing can damage it.
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More advice
- Looking After New Sealant: Aftercare Tips
- Can You Clean Black Mould Out of Silicone?
- How Long Does Silicone Sealant Last?
- All advice
This guide is general information about sealant work. It isn’t legal, fire-safety or structural advice; for those, speak to a qualified professional.