Water resistant is not waterproof
Start with the distinction that causes the most trouble. Maira Tile Bond 3100 is highly water resistant once hardened — which means water will not degrade the cured adhesive.
It does not mean the tiled surface is a waterproof barrier. Grout joints are not waterproof, and water passes through them. Where the design calls for a tanking or waterproofing membrane — wet rooms, shower enclosures, balconies over occupied space — that membrane does the waterproofing and the tiles go over it.
Treating a water-resistant adhesive as a substitute for tanking is the single most expensive mistake in this whole category, because you only find out years later, from the ceiling below.
Voids are worse in a bathroom
Elsewhere a void behind a tile is a weak point. In a wet area it is a reservoir. Water gets in through the joints, fills the gap, and stays there in the dark with nowhere to dry to.
That is why full bed contact matters more here than anywhere else. Comb in straight lines, press and slide each tile home, and back-butter anything large. The techniques are in why tiles sound hollow.
Falls and drainage
Water needs somewhere to go. Shower floors and wet room floors need a fall towards the drain, and that fall has to be built into the substrate before tiling — you cannot create it with adhesive.
Check the fall with a level before you start. Water that ponds on a flat floor will find the weakest joint eventually, and standing water is what turns a small defect into a leak.
Substrate comes first
The usual rules apply, and they matter more here: sound, clean, free of dust and grease, reasonably flat. Where a membrane is specified, it goes on before the adhesive, and the tiles bond to it.
Full guidance is in surface preparation before tiling.
Movement joints
Do not tile hard into corners and junctions. Perimeter joints, and the internal corners where wall meets wall or wall meets floor, should be left for a flexible sealant rather than filled with rigid grout. Those junctions move, and rigid material there cracks.
Choosing the colour
Bathrooms are where light tile and white grout are most common, and where a dark bed shows up worst — grey squeeze-out in a white joint is very hard to clean out and stains as it cures. Tile Bond 3100 comes in three colours:
More on matching them to your tile in white or grey tile adhesive.
Let it set before it gets wet
Grout only when the tiles are firmly set, and keep the room out of use until the adhesive and grout have properly hardened. Running a new shower the same evening is not worth the risk. Ask Ali Traders about timings for your conditions.
Note: the figures here are typical values for Maira Tile Bond 3100 and are given as guidance. Real results vary with substrate, tile format, trowel size, temperature and site conditions. Confirm quantities and working times with Ali Traders before you order or start work.