Being an American studying abroad for a semester, I was somewhat surprised (probably foolishly so) to find that something as simple as plumbing is, in fact, quite varied on the British Isles. Let me explain.
In America, the common way to bring water into a sink or bathtub is through two taps--one for hot water, one for cold--and one faucet. The taps are used to control the water pressure and the relative temperature of the water, which mixes in a single pipe and emerges from the spout. At least one drain is present at the bottom (often with a plug that is either attached to the sink via a chain or can be closed by pulling on a knob installed directly into the faucet), and in case of a sink there is usually a "safety drain" near the rim of the basin directly across from the faucet. A bathtub usually does not have a "safety drain" in the interest of keeping as much water actually inside itself as possible. A shower will have a grille instead, so that the constant stream of water can constantly drain without flooding the bathroom. Regardless of the drain species, American plumbing is built around the one-faucet-two-taps theory (excluding hotel showers, which were designed by a Lord of the Pit and tend to involve more funny knobs and dials than a 1950s television). I am ignoring the push-the-button or tag-the-sensor taps found in more futuristic truck stops for the sake of simplicity; this paragraph has gone on long enough.
British plumbing (and Scottish, and Welsh), however, has used no less than three different schemes of moving water from a holding tank onto either your hands or your naked body. One is the aforementioned push-the-tap scheme, although instead of a single faucet there are two, available in both bloody freezing and skin-searingly hot varieties (mixing the two is an exercise in futility; if your hands MUST be washed, just suck it in and do it quickly). The other two, however, are much more interesting.
Many sinks employ two taps, one for hot water and one for cold, but each has its own faucet. In some sinks the temperature can be moderated, but in my experience these were few; the washrooms of the UK were determined to make my unworthy American hands as inconveniencing as possible. Thankfully, those without much control over the heat of the water (you could mix the water a bit by splashing around, but it makes one look ridiculous) also tend to have grille drains, ensuring that the mean ol' agua will soon swirl away into nothingness, bearing soap bubbles.
The sort found in the campus showers--the showers that I used, at any rate--have two knobs, a circular grille drain, and the traditional plucked-sunflower shower head. The knobs themselves are rather odd. One is rather plebian, being the standard metal-thingy-that-turns; this knob controls the pressure of the water. The second is a knob with a bright red switch made from plastic; when at a perfectly balanced state of freezing water and broiling water, the little switch will clack into place. To make the water cooler, one pulls the switch (it slides back easily, so even the soapiest of thumbs can manage) and turns counterclockwise, and to make the water warmer the switch is pulled and the knob is turned clockwise. Temperature control can be handled independant of water pressure, so it's advisable to make sure the shower hasn't been left on "lobster boil" by the last bather.
I'm certain that other parts of Europe have even more fascinating lavatories, but my funds prevent me from exploring further. I am quite pleased to say that I have so far found NO occurances of "camping commodes"...those who are not familiar with an outhouse should consider yourselves blessed.
For those curious about the toilets, they're pretty much the same as any other toilet, with no funny dials or levers or intricate Rube Goldberg devices required to make them empty themselves. Maybe Europe doesn't hate me so much after all.