Updated July 5, 2026 · 7 min read
Tile itself is one of the lowest-maintenance surfaces in a bathroom — it is the grout between the tiles that does the aging. Cement-based grout is porous, so it absorbs water, soap, oils, and whatever else lands on it, and that absorbency is why grout darkens, stains, and grows mildew while the tile around it still looks fine.
The good news is that grout care is mostly about using the right products and a light, regular routine — not heroic scrubbing sessions. This guide covers what to clean with (and what the Tile Council of North America specifically says not to use), how sealing actually works, and how often to redo it.
This is a care guide for tile you already have. If you are still planning a remodel, our guides to tile mistakes to avoid and shower waterproofing cover the decisions that determine how much maintenance your tile will need in the first place.
Key takeaways
- Cement grout is porous — staining and mildew are absorption problems, so sealing and quick moisture cleanup matter more than scrubbing power.
- Use alkaline or purpose-made tile cleaners; TCNA specifically warns against oil/wax-based cleaners (Murphy’s Oil Soap, Pine-Sol) and acid-based cleaners, which dissolve cement grout.
- Choose a penetrating sealer for bathrooms — topical sealers trap moisture in wet areas and encourage mold.
- Reseal on a schedule: roughly every 6–12 months for showers and heavy-use areas, 2–3 years for low-traffic floors — and verify with the water-bead test.
- Mold that keeps coming back or grout that keeps cracking in a shower is a waterproofing symptom — clean less, investigate more.
Why grout — not tile — is the maintenance job
Per the Tile Council of North America (TCNA), cementitious grout is inherently porous: it absorbs water, oils, and biological material. That is the root cause of nearly every grout complaint — staining, darkening, and mildew all start with something soaking in. Epoxy grout, by contrast, is non-porous and does not need sealing, which is why it shows up in more premium installations.
This Old House makes the same point from the cleaning side: because grout is porous, it absorbs dirt and grease that can harbor bacteria and mold, and regular cleaning both keeps the surface sanitary and extends the grout’s lifespan.
What to clean with — and what TCNA says to avoid
TCNA’s guidance on grout cleaning is refreshingly specific. Alkaline cleaners (the Spic and Span / Mr. Clean family) and purpose-made tile-and-grout cleaners are the right tools, and the same cleaner that works on the grout generally works on the tile too.
Two categories to keep away from cement grout, per TCNA: oil- or wax-based cleaners like Murphy’s Oil Soap and Pine-Sol, which leave a waxy or oily film in the grout that then attracts dirt — and acid-based cleaners, because cement is alkaline and is dissolved by acids. A vinegar habit that is harmless on glass will slowly eat cementitious grout.
This Old House’s rule of thumb for the routine itself: always start with the mildest option — a soft brush and a gentle cleaner — and escalate only if that fails. A common DIY approach it describes is a paste of baking soda, dish soap, and water scrubbed in with a stiff grout brush or toothbrush.
The counterintuitive one: go easy on vinegar
Vinegar is the internet’s favorite bathroom cleaner, but cement grout is alkaline and acids dissolve it — TCNA warns against acid-based cleaners on cementitious grout, and This Old House likewise advises against vinegar on sealed grout. Save the vinegar for glass and fixtures; use an alkaline or neutral cleaner on grout lines.
Sealing: penetrating vs. topical sealers
Sealing is the single most effective thing you can do for cement grout, and TCNA describes it as "a very good idea" for stain prevention. There are two classes of sealer, and they behave very differently.
Penetrating sealers soak in and chemically bond with the grout, repelling water and water-based stains while leaving the grout’s texture and breathability intact. They cost more but hold up better, and they are the type generally recommended for wet areas.
Topical sealers coat the surface instead. They are cheaper, but per TCNA they give grout a plastic appearance, wear away under traffic, and are sensitive to moisture in the grout while curing. This Old House adds a sharper warning for bathrooms specifically: surface-coating sealers are not recommended in wet areas because they prevent water that gets behind them from evaporating — which encourages exactly the mold you were trying to prevent.
| Type | How it works | Best for | Trade-offs |
|---|---|---|---|
| Penetrating sealer | Soaks in and bonds with the grout; repels water and stains invisibly | Bathrooms, showers, wet areas | Costs more; can lock in existing stains if applied over dirty grout |
| Topical (surface) sealer | Coats the grout surface with a film | Dry, low-traffic areas | Plastic look, wears off, traps moisture — not recommended for wet areas |
Sealer classifications per TCNA and This Old House. Epoxy grout is non-porous and does not need sealing at all.
How often to reseal — and the 10-second test
Resealing frequency depends on how hard the area works. This Old House’s guidance: high-traffic and heavy-use areas every 6–12 months, low-traffic areas every 2–3 years — and light-colored grout benefits from annual resealing because it shows staining first. A shower gets "high-traffic" treatment even if the bathroom itself is rarely used, because it is wet daily.
You do not have to guess. The water-bead test This Old House describes takes ten seconds: drip a little water on a grout line. If it beads up on the surface, the seal is still working. If it soaks in and darkens the grout, it is time to reseal.
When you do reseal: clean the grout first, let it dry completely (about 24 hours after a deep clean), apply the sealer along the joints per the manufacturer’s instructions, and wipe any excess off the tile face before it dries.
The weekly routine that makes deep cleans rare
- Run the bath fan during and after showers — moisture is what grout mildew feeds on. Our bathroom ventilation tips cover the full moisture-control routine.
- Rinse shower walls after use so soap and shampoo residue does not sit on the grout lines and soak in.
- Wipe or squeegee tiled shower walls — the same habit that saves glass doors saves grout.
- Clean grout lines with an alkaline or neutral cleaner and a soft brush before they visibly darken — mild and often beats harsh and rare.
- Watch for cracked or crumbling grout lines and failed caulk at the joints — those are water entry points, not just cosmetic flaws. Our caulking guide covers the joints grout should never fill.
When cleaning is no longer the answer
Some grout problems are past the point of cleaning. This Old House’s list of signs to bring in a professional: mold that returns quickly after cleaning, persistent foul smells, cracked or damaged grout, and stains that survive repeated cleaning. Cracked grout in a shower is the most urgent of these — it can be the visible symptom of water getting behind the tile, which is a waterproofing problem, not a cleaning problem.
If your shower grout keeps failing in the same spots, read our shower waterproofing guide — the fix may be behind the wall, and no amount of regrouting will hold if the substrate is wet.
Frequently asked questions
- What should I not use to clean grout?
- Per the Tile Council of North America: avoid oil- or wax-based cleaners like Murphy’s Oil Soap and Pine-Sol, which leave a film in the grout that attracts dirt, and avoid acid-based cleaners — cement grout is alkaline and acids dissolve it. That includes leaning on vinegar as a routine grout cleaner. Use alkaline household cleaners or purpose-made tile-and-grout cleaners instead.
- How often should bathroom grout be resealed?
- Per This Old House, high-traffic and heavy-use areas need resealing roughly every 6–12 months, and low-traffic areas every 2–3 years — with light-colored grout benefiting from annual treatment. The simple check: drip water on a grout line. If it beads, the seal is fine; if it soaks in and darkens, reseal.
- Does epoxy grout need to be sealed?
- No. Per TCNA, epoxy grout is non-porous and does not require sealing — that stain resistance is a big part of why it is specified in premium showers. Only cementitious (cement-based) grout needs a sealer.
Sources
- Tile Council of North America — Cleaning Grout (FAQ)
- This Old House — Protecting Grout After an Installation
- This Old House — How To Clean Grout
Claims and figures are drawn from the sources above and provided for general guidance; your project may vary. Photography is illustrative of design concepts. For a fixed price on your specific bathroom, request a free estimate.
