Have you ever noticed a white powdery substance on your grout? It might seem like a small cosmetic issue, but it’s actually telling you something important about your home. This build-up, known as efflorescence, signals that there may be underlying problems with your tiles and grout.
We encounter this issue frequently during inspections or when homeowners send us photos asking for advice. That’s why we decided to write this article to shed light on what’s really happening.
Let’s explore what efflorescence is, why it happens, and what it means for your home.

What is the White Build-Up on Grout?

Efflorescence is the term used to describe white, powdery salt deposits that appear on the surface of grout and tiles. This occurs when water travels through the grout, dissolving salts along the way. As the water evaporates at the surface, it leaves these salts behind.


Outdoor tiles with significant efflorescence, showing white streaks and patches on grout lines due to water ingress.

Grout efflorescence on outdoor tiles: Addressing the white streaks and patches caused by moisture problems.

Why Efflorescence Indicates a Bigger Issue

Efflorescence is more than just some powder to be cleaned off; it suggests that water is getting where it shouldn’t be. Here’s what it is telling you:

  1. Screed Issues: The minerals causing the white deposits are coming up through the screed, indicating that the screed itself has been affected by moisture. This can weaken the structure and adhesion of your tiles.
  2. Potential Signs of Compromised Waterproofing: If you see stains on the ceiling below a 2nd floor, wet carpet, mouldy smells, or spongy, squishy, or crunchy floor tiles, these could indicate that the subflooring is about to give way. If you notice these signs, then yes, the waterproofing has likely been compromised.

How Do You Remove Calcium Deposits from Grout?

While removing the white deposits can improve the appearance of your tiles, it’s essential to address the root cause. Here’s a quick guide to cleaning:

  • Dry Brushing: Use a dry, stiff brush to remove loose deposits.
  • Acid Cleaning: Apply a solution of white vinegar and water (1:1 ratio) to the affected areas. Let it sit for about 10 minutes, then scrub and rinse thoroughly.
  • Commercial Cleaners: For stubborn deposits, use a commercial efflorescence cleaner, following the instructions carefully.

Why Cleaning Isn’t Enough

While cleaning might seem like a quick fix, it doesn’t address the underlying issue. Many people think that sealing the grout will solve the problem, but if the waterproofing layer is compromised, the issue will persist. It’s crucial to get to the root of the problem to prevent further damage.

The Right Approach to Fixing Efflorescence

To properly address efflorescence, consider the following steps:

  1. Inspection: Have a professional inspect the area to determine the extent of the water ingress and damage. Make sure you call someone with moisture meter equipment who can conduct a thorough leak inspection.
  2. Sealing the Tiles: If the inspection indicates that the waterproofing membrane is still intact, sealing the tiles is a possible option. Using epoxy grout is recommended for lasting results, as it is highly resistant to water and stains.
  3. Repair the Waterproofing: If the waterproofing layer has failed, it will need to be repaired or replaced. This often means removing the tiles and screed to apply a new waterproofing membrane.
Efflorescence on terracotta tiles with white calcium deposits along grout lines, indicating water ingress issues.

Efflorescence on terracotta tiles: White calcium deposits indicate potential waterproofing issues.

Preventing Future Build-Up

Preventing efflorescence starts with good installation practices and regular maintenance:

  • Use Quality Materials: Invest in high-quality tiles, grout, and waterproofing materials.
  • Proper Installation: Ensure that tiles and waterproofing are installed correctly by experienced professionals. We say it all the time but we’ll say it again – when it comes to wet surfaces, you can’t afford to take shortcuts – you get what you pay for.
  • Regular Maintenance: Keep your tiles and grout clean and well-sealed to prevent water penetration. Inspect the grout every year to ensure no holes are allowing for minor leaks to become a bigger problem.

Calcium build-up on grout is more than just a surface problem; it’s a sign that there could be significant issues beneath your tiles. While cleaning might offer a temporary solution, addressing the underlying cause is essential to maintaining the integrity and longevity of your tiled surfaces. By understanding and tackling the root of the problem, you can ensure your home remains beautiful and structurally sound.

So, next time you spot that white powder on your grout, take it as a signal to investigate further. Your tiles – and your home – will thank you for it.