Floor for outdoor shower?

Hi, all.  We're planning to build an outdoor shower and I'm hoping to get some advice from you smart people.   
"Outdoor shower season" is the long, dry, hot summer.  The shower will be under some established citrus trees, and will be surrounded by other plants.  For the floor, we're thinking of doing a bed of gravel/pebbles (maybe 4-6"?) with larger, flat stones to stand on so the floor is permeable and the water will just drain down to the soil.  (We're thinking of avoiding a wooden floor because we don't want black widows camping out underneath.)  I have never seen any part of our property fail to soak up water (there's no standing water or boggy ground here), so I can't imagine we would have issues with lack of drainage in the soil.  Does anyone have thoughts on permeability issues with the gravel, whether it would be better to have the water dispersed through a pipe system rather than just draining down, whether something different altogether would be better, etc.?  Many thanks for any contributions!

Depending on how hot and dry your summers are, you might want to collect the water or direct it in some way to where it will water plants.  Just letting it soak in to one spot, especially if it gets saturated seems like it might be a waste of water to me.

I used a 4-gallon pump sprayer of a shower for a while.  I just took it to someplace that needed the extra water and sprayed myself off.

Depending on how dry the summers are, it might be good to let the shower water drain into a large compost pile.

The pile could also have coils of polyethylene pipe or garden hose in it, to feed the "hot" intake of the shower head.

This might mean grading & lining the soil under the showerhead, before the permeable floor goes down, and digging out a composting trench (similar to the Indore method, but perhaps not lined) for the water to drain into. Perhaps plant a hedge of willows on the other side of the trench, to catch any leachate, to help with privacy, and to help feed the compost pile.

Alternatively, wisteria loves moisture, and can produce a lot of nitrogen & biomass each year. If the shower structure is built sturdily enough, its can be trained up it provide some nice shade.

I cut a 55-gallon plastic barrel in half and sunk it under the shower floor.  plumbed the two bungs to drain to grey water, but leave about six inches of water in the bottom for some aquatic plants to grow around the shower.  the barrel halves are filled with 3/8" to 1" round rock a couple inches above their tops so the plastic is invisible, and the floor proper is made out of salvaged redwood from a sauna across the street treated with a few coats of tung oil for extra rot resistance (woodworkers reading this: sorry if I've committed an offense there).  some of the shower water is going to splash beyond where the barrels can capture it, so I'll plant some more moisture loving stuff there.  I was thinking more along the lines of akebia and jasmine for vines and privacy and lovely smells, but wisteria sounds nice, too.

I like the flat stone floor idea.  just make sure the stones aren't slippery when wet and soapy.

draining directly into the soil: I guess that depends on your soil and the plants nearby.  if the shower is going to be close enough to those citrus trees you mentioned, and your soil isn't excessively well drained, then I guess the simplicity would be nice.  if it's just going to drain directly to the water table and there aren't plants close by to use the water, a slightly more complex system might be in order.

sounds like a very nice project.

Great ideas here; thanks for the feedback.  We're thinking about planting tropical plants around the shower that need more water than we'd be willing to give them otherwise (banana, mango, etc.).  I'm thinking that the roots will just seek out the water wherever it ends up, but perhaps it would be better to direct the water to the outer border of the shower so the roots don't have to grow underneath.  I'll post again when I see how things go in case anyone else is interested.

OK so here is my plan for an outdoor shower. Please advice on potential problems.
So the plan is to build a 4'x4' box put in a shower pan then basically use a pallet like structure over to stand on. Prolly gonna fill with 3/4" gravel. Then i will direct the grey water into a holding tank for garden use. i want to use a 275 gal bladder in a cage for the water tank on both ends.

So i guess the questions i have are: is the gravel a good idea, and is there any problem with bath products going into the garden

It's better not to put grey water into a holding tank. If kept for more than a few hours, grey water can turn to black water. It's best to direct it to planted areas immediately.

A good reference for anything to do with grey water: http://oasisdesign.net/greywater/index.htm

Thanks Tyler for the responce and for the info/link