There is no way to make tile and grout waterproof. A correct fix will involve fixing the waterproof layer under the tile, anything else is a bandaid. Is the waterproofing under the tile pitched at least 1/4'' per foot to a drain or off the deck? Same question for the tile.
PROGRIP WATER REPELLENT TILE GROUT Is a specially formulated grouting compound with exceptional water repellent properties, making it ideal for use in permanently wet as well as underwater conditions, i.e. swimming pools and showers.
The most likely place for the water to be seeping in behind the tile is where the walls meet the floor. This transition should be caulked with silicone caulking. You can use either clear or a color matched caulk if one is available.
Either you don't have a vapor retarder or it was installed in correctly. You could remove the grout and install an impervious epoxy grout or an ASTM C920 sealant in the grout joints to make it water tight, but the water migration can still cause problems to the marble.
Whoever installed your floors most likely did not seal the grout because it needs time to harden and cure completely.
Vinegar can indeed ruin grout.
Once lodged in these spaces, vinegar will corrode grout with the passage of time. The grout will eventually wear off. So you should take not to apply vinegar for cleaning purposes if you have unsealed grout in the area.
Being naturally water-resistant, Epoxy grout is an excellent choice if you plan on laying tiles in your front or back garden. Epoxy grout is made up of a unique blend of a filler powder form grout and epoxy resins, making it the best grout to use for outdoor projects.
The bad news is that if your tile floor is already installed, it's impossible to fully waterproof it unless you're willing to remove the tile, put a waterproof membrane in place, and then reinstall the tile. Waterproofing membranes come in rolled-up strips that you lay on your floor and cut to the correct size.
With sufficient maintenance and care, your grout color sealer can last up to ten years or even more. Apart from maintenance, your grout's lifespan also depends on the type of product. To keep it clean and crisp, avoid using solvent-based paint strippers to the tile as they can remove the grout paint.
While the tile industry does not require sealing, it is always recommended, especially in wet or high-traffic areas. Penetrating sealers are the most commonly used and offer high water, chemical and stain resistance. They provide protection without changing the appearance of the grout joint.
In a situation where new tiles will be installed over existing tiles, a layer of waterproofing membrane can be applied via the following methods: Waterproof coating – The membrane is in liquid form that is adhesive over existing tiles. It forms a barrier that prevents water from entering the existing tile joints.
Bear in mind, grout is not waterproof, only water resistant and once cracked, water is most assuredly going to get behind it and probably damage the wall, unless the wall or floor was properly sealed with something like Kerdi first.
It is important not to leave any excess sealer on the tile surface because it won't get absorbed and it can leave a sticky surface that can become a maintenance problem.
It is generally better to use brushed grout sealer than spray sealer as you can apply more sealer with more control.
Many companies don't automatically include grout sealing in a job with new tile flooring for a few reasons. First, companies can't seal grout until at least 48 to 72 hours after applying grout. By that time, bathroom remodelers typically have already cleaned up from the job and left your home.
Unsightly Grout Stains and Discoloration:
One of the most noticeable effects of neglected grout sealing is the gradual accumulation of stains and discoloration. Grout is porous by nature, which means it readily absorbs liquids, dirt, and debris.
To seal to perfection, we recommend using Universeal Grout and Tile Protector. This product is a solvent based sealer designed to deeply penetrate your grout. It is effective in preventing stains from oil and water-based liquids and it will not discolour your tiles.
epoxy grout is a great choice when you are ready to re-grout a tile project. Because epoxy grout is so much stronger than other types of grout (particularly cement grout), you won't even need to remove all of your old grout. You can apply new grout right over the top of the old grout.
Standard grout isn't waterproof at all, only epoxy grout is. You can seal regular grout after it dries, but you have to do it every so often or else the grout will begin to absorb water again.