Waterproof Grout: The Best Options for Showers, Bathrooms, and Wet Areas

Standard cement-based grout is porous. It absorbs water, stains, and eventually becomes a breeding ground for mold and mildew — especially in showers and other wet areas. Waterproof grout solves this problem by creating a non-porous, water-resistant joint between tiles that stays clean and intact for years.

This guide covers the main types of waterproof grout, how they compare, the best brands, application tips, and pricing so you can choose the right product for your tile flooring or shower project.

Why Standard Grout Fails in Wet Areas

Traditional Portland cement grout — both sanded and unsanded — is naturally porous. Even when sealed, it absorbs moisture over time. In a shower that runs daily, this leads to several problems:

• Mold and mildew growth: Moisture trapped in porous grout feeds mold, causing discoloration and health concerns
• Staining: Soap scum, hard water minerals, body oils, and cleaning products penetrate the grout surface
• Cracking and crumbling: Repeated wet-dry cycles cause cement grout to deteriorate, especially in shower floors and curbs
• Efflorescence: Mineral deposits from water migrating through the grout appear as white, chalky stains

Waterproof grout eliminates these issues by replacing or supplementing the porous cement matrix with water-impervious materials.

Types of Waterproof Grout

Epoxy Grout

Epoxy grout is the gold standard for waterproof grout. It is made from epoxy resins and a hardener (no Portland cement), which creates a non-porous, chemical-resistant joint that is essentially impervious to water.

Key properties:

• 100% waterproof — zero water absorption
• Extremely stain-resistant (resists acids, oils, grease, and most chemicals)
• Does not require sealing — ever
• Bonds strongly to tile edges
• Available in sanded and non-sanded formulas
• Color-consistent and fade-resistant

Limitations:

• More difficult to work with than cement grout — shorter working time (30 to 45 minutes)
• Can be challenging to clean off tile surfaces if not wiped promptly
• Slightly glossy finish that differs from the matte look of cement grout
• Higher cost than cement-based products
• Not recommended for natural stone with a polished finish (the epoxy can haze the stone surface)

Best for: Showers, steam rooms, kitchen backsplashes, pool surrounds, commercial kitchens, and any area with constant water exposure.

Top brands: Laticrete SpectraLOCK, Starlike EVO (Litokol), Mapei Kerapoxy, Prism by Custom Building Products.

Cost: $5 to $12 per pound (covers approximately 20 to 40 square feet per unit, depending on tile size and joint width).

Urethane Grout (Pre-Mixed)

Urethane grout is a single-component, pre-mixed product that comes ready to use straight from the container. Unlike epoxy, there is no mixing of separate components. It uses a urethane binder instead of cement, making it water-resistant (though not as impervious as epoxy).

Key properties:

• Highly water-resistant (not 100% waterproof but far better than cement grout)
• Pre-mixed — no measuring or mixing required
• Flexible — accommodates minor tile movement without cracking
• Stain-resistant without sealing
• Easier to work with than epoxy grout
• Color consistent — no shade variation between batches

Limitations:

• Not as fully waterproof as epoxy
• Shorter shelf life once opened
• Slightly rubbery texture when cured
• Cannot be used for joints wider than 1/2 inch
• More expensive than cement grout

Best for: Bathroom floors, kitchen floors, backsplashes, and areas with regular but not constant water exposure. A good compromise between cement and epoxy grout.

Top brands: Bostik TruColor, Prism SureColor, QuartzLock2.

Cost: $30 to $60 per gallon (covers approximately 50 to 100 square feet).

Grout Sealers (Making Cement Grout Water-Resistant)

If you already have cement grout installed, or prefer to install cement grout for its workability and lower cost, grout sealers can add a water-resistant barrier. There are two main types:

Penetrating (Impregnating) Grout Sealers

Penetrating sealers soak into the grout pores and line them with a water-repellent silicone, siloxane, or fluoropolymer coating. Water beads up on the surface instead of being absorbed.

• Does not change the appearance of the grout
• Allows the grout to breathe (vapor permeable)
• Lasts 3 to 5 years before reapplication is needed
• Does not make grout fully waterproof — reduces absorption rather than eliminating it

Top brands: Aqua Mix Sealer’s Choice Gold, Miracle Sealants 511 Impregnator, TileLab Grout and Tile Sealer.

Cost: $15 to $40 per quart (covers 200 to 500 square feet).

Topical (Surface) Grout Sealers

Topical sealers create a film on the surface of the grout that blocks water penetration. They provide better waterproofing than penetrating sealers but can alter the appearance (adding sheen) and may peel or wear off in high-traffic areas.

• Stronger water barrier than penetrating sealers
• May add a glossy or semi-gloss finish
• Can trap moisture beneath the surface if applied to damp grout
• Needs reapplication every 1 to 3 years

Best for: Countertops, backsplashes, and light-use areas where appearance enhancement is desired.

Waterproof Grout Comparison

Here is how the main waterproof grout options compare across key factors:

• Water resistance: Epoxy (excellent) > Urethane (very good) > Sealed cement (moderate)
• Stain resistance: Epoxy (excellent) > Urethane (very good) > Sealed cement (moderate)
• Ease of application: Urethane (easy) > Sealed cement (easy) > Epoxy (difficult)
• Cost: Sealed cement (lowest) > Urethane (moderate) > Epoxy (highest)
• Durability: Epoxy (25+ years) > Urethane (15-20 years) > Sealed cement (needs re-sealing every 3-5 years)
• Maintenance: Epoxy (lowest) > Urethane (low) > Sealed cement (periodic re-sealing)

Best Waterproof Grout for Showers

For showers specifically, the recommendation is clear: epoxy grout is the best choice. Here is why:

• Showers receive daily water exposure — sometimes multiple times per day
• Steam and standing water on shower floors test grout constantly
• Mold thrives in the warm, moist environment of a shower — only non-porous grout truly prevents it
• Shower grout is difficult to access for resealing, so a product that never needs sealing is ideal
• Cleaning chemicals used in showers (bleach, acidic cleaners) can damage cement grout but not epoxy

If epoxy grout is not an option (due to budget or DIY skill level), urethane grout is the next best alternative for showers. Cement grout with a quality penetrating sealer is a distant third choice and will require ongoing maintenance.

Application Tips for Waterproof Grout

Epoxy Grout Application Tips

1. Work in small sections: Mix only enough epoxy for 10 to 15 minutes of work. It hardens quickly.
2. Keep a bucket of clean water and sponge handy: Wipe tile surfaces frequently to prevent epoxy haze.
3. Use a hard rubber float: Epoxy is stickier than cement grout and requires more force to push into joints.
4. Clean tools immediately: Cured epoxy is nearly impossible to remove from tools.
5. Temperature matters: Work in 60 to 80 degree F conditions. Heat accelerates curing and shortens working time.
6. Final cleaning: Use the manufacturer’s epoxy haze remover within 24 hours if any residue remains on tiles.

Urethane Grout Application Tips

1. Do not add water: Urethane grout comes pre-mixed. Adding water weakens it.
2. Let it skin over slightly before sponging: Wait about 15 to 20 minutes after packing joints before the first wipe.
3. Use minimal water when cleaning: Excess water can wash urethane out of the joints.
4. Do not apply to wet tiles: Tile surfaces and joints should be dry before application.
5. Seal the container: Urethane grout can dry out once opened. Seal tightly between uses.

Waterproof Grout Pricing Summary

For a typical bathroom with 100 square feet of tile, here are approximate grout costs:

• Cement grout + sealer: $20 to $50
• Urethane grout: $40 to $80
• Epoxy grout: $60 to $150

Professional grout installation labor runs $5 to $10 per square foot, which is typically included in the tile installation quote. Regrouting an existing waterproof tile installation costs $10 to $25 per square foot due to the additional labor of removing old grout.

Frequently Asked Questions

Can I apply epoxy grout over existing cement grout?

No. Old grout must be removed (at least to a depth of 2/3 the tile thickness) before applying epoxy grout. Epoxy does not bond well to old cement grout surfaces.

Does waterproof grout eliminate the need for a waterproof membrane?

No. Waterproof grout prevents water from passing through the grout joints, but a proper waterproofing membrane (like Schluter Kerdi, RedGard, or Laticrete Hydro Ban) behind the tile is still essential in showers and wet areas. Grout and waterproofing membranes work together as a system.

Can I use waterproof grout with natural stone?

Urethane grout and grout sealers work well with natural stone. Epoxy grout can be used with natural stone, but test it on a sample first — some polished stones can be hazed by epoxy residue that is difficult to remove.

How long does waterproof grout last?

Epoxy grout can last 25 years or more without maintenance. Urethane grout lasts 15 to 20 years. Sealed cement grout needs resealing every 3 to 5 years to maintain its water resistance.

Final Thoughts

Investing in waterproof grout — especially for showers and high-moisture areas — pays for itself many times over in reduced maintenance, better hygiene, and longer-lasting tile installations. Epoxy grout is the top performer, urethane grout is the user-friendly alternative, and quality grout sealers are the minimum you should apply to any cement grout in a wet environment.

The small cost premium for waterproof grout over standard cement grout is one of the smartest investments you can make in a tile project.