Tile & Grout Care: How to Clean, Seal, and Protect a Tiled Bathroom

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, which is the shared root cause behind staining, darkening, and mildew growth. Epoxy grout is the exception: it's non-porous and never needs sealing, which is why it turns up more often in premium, low-maintenance shower builds.

This Old House makes the same point from the cleaning angle: because grout is porous, it absorbs dirt and grease that can harbor bacteria and mold, so a regular cleaning routine does double duty — it keeps the surface sanitary and extends how long the grout itself lasts.

What to clean with — and what TCNA says to avoid

TCNA's cleaning guidance is more specific than most people expect. Alkaline cleaners (the Spic and Span / Mr. Clean family) and purpose-built tile-and-grout cleaners are the right tools, and a cleaner that works on grout generally works fine on the surrounding tile too.

Two categories to keep off cement grout entirely, per TCNA: oil- or wax-based cleaners like Murphy's Oil Soap and Pine-Sol, which leave a residue in the grout that then attracts more dirt — and acid-based cleaners, since cement is alkaline and acids break it down chemically. A vinegar habit that's perfectly safe on a glass shower door will slowly dissolve cementitious grout over repeated use.

This Old House's rule for the routine itself: start with the mildest option — a soft brush and a gentle cleaner — and only escalate if that fails. A common DIY method it describes is a paste of baking soda, dish soap, and water, worked in with a stiff grout brush or an old toothbrush.

Sealing: penetrating vs. topical sealers

Sealing is the single most effective step for protecting cement grout, and TCNA calls it "a very good idea" for stain prevention. There are two categories of sealer, and in a bathroom that stays damp for hours after every shower, the difference between them matters more than in a drier climate.

Penetrating sealers soak into the grout and chemically bond with it, repelling water and water-based stains while leaving the grout's natural texture and breathability intact. They cost more up front but hold up longer, and TCNA generally points to them as the right choice for wet areas.

Topical sealers sit on top of the grout as a surface film instead. They're cheaper, but per TCNA they give grout a plastic look, wear away under foot and water traffic, and are sensitive to moisture in the grout while curing. This Old House adds a sharper warning specific to bathrooms: surface-coating sealers aren't recommended in wet areas because they trap moisture that gets behind them and prevent it from evaporating — which invites exactly the mold problem the sealer was meant to prevent, and is a real risk in a climate this humid.

How often to reseal — and the 10-second test

Resealing frequency tracks how hard the area works and how much moisture it sees. This Old House's guidance: high-traffic and heavy-use areas every 6–12 months, low-traffic areas every 2–3 years — with light-colored grout benefiting from annual resealing since it shows staining first. A daily-use shower earns "high-traffic" treatment even in a rarely used guest bathroom, simply because it's wet every single day.

You don't have to guess on timing. The water-bead test This Old House describes takes ten seconds: drip a little water onto a grout line. If it beads on the surface, the seal is still doing its job. If it soaks in and darkens the grout, it's time to reseal.

When resealing: clean the grout thoroughly first, let it dry completely — about 24 hours after a deep clean, longer in a humid bathroom with limited airflow — apply the sealer along the joints per the manufacturer's instructions, and wipe any excess off the tile face before it sets.

The weekly routine that makes deep cleans rare

• Run the bath fan during and well after showers — a Pacific Northwest bathroom rarely gets a dry stretch on its own, and moisture left sitting is what feeds grout mildew. Our bathroom ventilation tips cover the full moisture-control routine.
• Rinse shower walls after use so soap and shampoo residue doesn't sit on the grout lines and soak in.
• Squeegee or wipe tiled shower walls — the same habit that keeps a glass door spot-free protects grout too.
• Clean grout lines with an alkaline or neutral cleaner and a soft brush before they visibly darken; mild and frequent beats harsh and rare.
• Watch for cracked or crumbling grout and failed caulk at the joints — those are water entry points, not just cosmetic flaws. Our caulking guide covers the joints grout should never be asked to seal.

When cleaning is no longer the answer

Some grout problems are past the point where cleaning helps. This Old House's list of signs to call in a professional: mold that returns quickly after cleaning, a persistent musty smell, cracked or crumbling grout, and stains that survive repeated attempts. Cracked shower grout is the most urgent of these — it can be the visible symptom of water working its way behind the tile, which is a waterproofing problem, not a cleaning one.

If your shower grout keeps failing in the same spots despite a good care routine, read our shower waterproofing guide — the real fix may be behind the wall, and no amount of regrouting holds up if the substrate underneath stays wet.