How to Clean Grout

While tile is typically stain-resistant, the type of grout that is placed between tiles will determine how susceptible the grout is to stains. There are three main types of grout: sanded grout, unsanded grout and epoxy grout.

Sanded grout and unsanded grout (also known as cementitious grout) both have a cement base, but unsanded grout is less gritty because it contains finer particles of sand. While sanded grout is best applied to tile joints that are one-eighth inch (0.3175 centimeters) wide or wider, such as floor tiles, unsanded grout is designed for use in gaps that are narrow, such as shower tiles or backsplash tiles. Both sanded and unsanded cementitious grout need to be sealed with waterproofing sealer upon installation and again every few years to ensure they remain as impervious as possible to stains.

Epoxy grout is made from a mixture of epoxy resin, silica fillers, colored pigments and a hardening agent. Epoxy grout also comes in sanded or unsanded versions. Epoxy grout does not need to be sealed so it is considered less susceptible to stains.

The unfortunate truth, though, is that all grout — whether cementitious or epoxy — is apt to stain.

A good rule of thumb for cleaning grout is "first, do no harm." Cleaning concoctions, even homemade cleaning mixtures, that contain highly acidic or alkaline ingredients may break-down the sealant that is protecting the grout from stains in the first place. And once this seal is breached, these harsh cleaners will start dissolving the grout itself.

The pH spectrum ranges from 0 to 14, with acidic liquids assigned lower numbers and alkaline liquids assigned higher numbers. A neutral pH is right in the middle of the range at "7." Lemon juice and vinegar, for example, are both highly acidic liquids with a pH value of "2," while chlorine bleach is highly alkaline with a pH value of 12.

Generally speaking, acid-based cleaning solutions are best for polishing metal fixtures or removing hard water deposits. Alkaline-based cleaning solutions can be used to cutting through grease or removing a build-up of grime. But when it comes to cleaning grout, it's best to start with a mild cleaning solution, one that isn't too far on either side of the pH range.

Here are the steps to take, from the simplest, to those that will tackle the grimiest situations, for cleaning your grout:

1. Start with water

The mildest cleaning solution is as simple as it gets: water. Start by spraying the grout lines with warm water; the grout should be damp but not soaked. Then use a nylon brush with soft- to medium-bristles to scrub the damp grout in a circular motion. Once you've thoroughly scrubbed the grout lines, wipe them dry. You don't want them to stay wet or you'll risk the development of mildew.

2. Up the ante with vinegar and water, but know the risks

If the grout still looks stained, you can up the acidity level of the cleaning product by using a diluted vinegar and water mixture in a spray bottle — but be sure you understand the risk. If the grout is unsealed, or has not recently been resealed, do not use even a diluted form of vinegar to address stains.

The acidic vinegar will dissolve the grout. Even grout that is sealed is at risk from cleaning solutions that contain vinegar. The same is true of cleaning solutions that contain lemon or other liquids with a low pH value — or cleaning solutions with bleach or ammonia that contain a high pH value. All are potentially damaging to grout.

If it is worth the risk to potentially damage the sealant or grout in order to address a stain, then it may be worth a one-time use. Keep in mind, however, that many grout and tile experts warn against using vinegar on floors or grout. If you decide to proceed, some cleaning experts recommend a one-to-one mixture of vinegar and warm water that could be sprayed on sealed grout and then scrubbed with a brush.

3. Try a baking soda paste

If this mixture still doesn't rid the grout of stains, the grout lines could be covered with a baking soda/water paste and then sprayed with a diluted vinegar/water solution and scrubbed. If the grout is unsealed, use the baking soda/water paste without the vinegar spray. Scrub and wipe dry.

4. Move to a baking soda/hydrogen peroxide paste

Really stubborn sealed or unsealed grout stains could be addressed with a baking soda/hydrogen peroxide paste. Apply the homemade paste and lightly scrub, let it sit for a few minutes, then rinse clean and wipe dry.

5. Last resort: Over-the-counter commercial stain remover

For deeply stained grout that simply won't lift, particularly for mold and mildew stains, an over-the-counter commercial stain remover may be necessary.

6. Steam cleaning is also an option

If you're leery of using acid- or alkaline-based cleaners that could potentially damage grout with repeated use, then steam-cleaning may be the best option. A steam cleaner is a power tool that heats water to more than 200 degrees Fahrenheit (93 degrees Celsius) and then uses nozzle or brush attachments to direct steam to areas that need cleaned, such as grout lines. Because the steam cleaner relies superheated water to lift and remove stains, you won't run the risk that comes with acidic or alkaline cleaning solutions.