From the measure-twice, cut-one school of philosophy:
If you've got some spare tiles on hand for repair or just leftovers from installing them, it's helpful to drill a test hole so that you get a sense of the tiles response to drilling and the pressure and time required to make the hole. It's also a good way to make sure that the bit size is sufficient for the anchor.

i have a fiberglass tub surround. does this work with that kind of "tile?" it's all one unit and it's probably pretty far off the wall studs. has anyone ever done that? we don't have many products to store so it's not a big deal, but someday i'd like a nicer showerhead spray thing.

Does this work the same way for a marble bath?

Billy Mays knows how!

https://www.mightyputty.com/spark/index.php?ai=42&tag=mpsc100

"i have a fiberglass tub surround. does this work with that kind of "tile?" "

No, it won't work as there is basically nothing behind the fiberglass for the shelf/hook/whatever to grip onto, and the fiberglass itself will flex, crack and break.

Even if you were lucky enough to find a spot that had a stud behind it (a 1 in 16 chance?) that 1" gap will cause the fiberglass to flex and crack between your hardware and the wood stud.

"Does this work the same way for a marble bath?"

Yes, tho you may need a different drill bit.

Where is the shelf from? It is exactly what I have been looking for.
Also, is it necessary to find the studs or does the tile itself offer enough support?

That shelf is perfect. I'd love to know where it comes from too !

We have a situation in our bathrooms where tile was installed over existing tile. Are there plastic anchors long enough to handle two layers of tile? And will a shelf or tp holder be stable when installed over two layers of tile? I'm intimidated.

"is it necessary to find the studs or does the tile itself offer enough support?"

"Are there plastic anchors long enough to handle two layers of tile? And will a shelf or tp holder be stable when installed over two layers of tile?"

Remember that you are hanging a shelf for some soap and a couple towels, not a hook for a boat anchor...

If the tile isn't falling off the wall, then it's secure enough for a little shelf. Go to your local neighborhood hardware store and tell the nice folks there what you're planning on doing - they'll help make sure you have the correct supplies.

Does Mighty Putty really work? I'm thinking about using it to hang a towel rod....

but does water seep in slowly?

I would totally opt to use mighty putty before doing any drilling...

Why don't they make tiles with pre drilled holes?

Please don't forget to drip water onto the hole your drilling. It get's hot and can cause a fire. The 2 in 1 drill guide and water drip can be bought at almost any hardware store and really helped me out.

Yes, not a masonry bit. That's for bricks. Use a tile bit, and get 3 or 4 so you always have a sharp one. i use a nailset to break the surface, drill at a low speed, and keep a spray bottle for cooling the bit. (you don't need the water drip/guide, but they do work)

I also cheat and use the grout whenever possible although it's not quite so aesthetically pleasing. As for level, it can be really tricky. Especially with brackets in which the screws fit into a keyhole slot...

my boyfriend and i are moving into an apt. this weekend, and the bathroom is entirely tile walls, with no shelving or storage whatsoever (not even a cabinet under the sink). i found these on the container store website, supposedly they can be used on tile without having to drill...
http://www.containerstore.com/shop/kitchen/magicLocSuctionCupRailSystem?productId=10025812

anyone have any thoughts? if they work, they would be a lifesaver, since i have gotten very used to have shelves in my bathroom...

This is a great tutorial, takes the scare factor out of a tile wall.

i'd like to add that this bit is amazing, i've used it for dozens of holes in tile so far, and it might be useful for those folks drilling through denser material like porcelain etc.

http://www.amazon.com/Hitachi-728023-1-4-Inch-Diamond-Cooling/dp/B000NK9G98/ref=pd_bxgy_hi_text_b

the water thing is useless in my experience, and you can get the bit separately at Lowes, for about $10.

ariellie, I clicked on the "more information" link for those shelves you mention and the pop-up read, "When properly installed on a non-porous surface, Magic-Loc discs offer an extremely firm grip, even on rough and slightly uneven surfaces, without the use of tools or screws! Non-porous surfaces include: glass, mirrors, tile, steel, sealed granite, melamine and varnished woods. The discs are also completely repositionable. The weight capacity for each Magic-Loc disc is 7 pounds (14 pounds for two discs) and the guaranteed holding time on a proper surface with proper installation is at least 6 months. After that time, it is recommended to remove the system from the wall and reapply the discs. Please see the product packaging for more information."

You should be fine using them as long as you don't put too much weight on them.

I may be suction cup-challenged, but I've never been able to get the suction cup storage and hooks to work, even following the directions v-e-r-y carefully. For those who do - what's the secret?

An alternative would be to use the 3M command hooks - which work very well on walls, not sure if they have special ones for tile or the regular work there too? and hang baskets from them...you could even use the same wire baskets from the suction cup thing, just removing the suction cups.

Word of warning from someone who used to have a glass shelf in my shower (installed by a previous resident): over time, the mounting hardware may rust and/or corrode.

I took my shelf off just to try and tighten things up (it had been sagging) and found the cause of the sagging was because the hardware had fallen apart over time.

I don't think a lot of these glass shelves are meant to be exposed to lots of water over many years.