X10 works, but is a pretty bad protocol. It is very slow and limited, and is susceptible to noise and interference (often mistaking noise for actual commands, causing lights to turn on/off on their own).
Z-Wave provides similar capabilites, but is much newer and uses RF signals to communicate. There are a huge variety of products and lots of stuff for UK (some stores I found on Google -- no endorsement: Z-wave products UK, UK Automation)
UPB is another technology, though it doesn't appear to be available in Europe.
Insteon is a fairly popular one in North America, and although they've been talking for a few years about introducing it to Europe, it doesn't appear they have yet.
All of these (including X10) have ways to communicate with them from a PC, and from there you're limited only by your imagination and programming abilities. I have an Insteon setup in my basement home theater, which is controlled by a PC (and via the PC, can also be controlled from a simple iPod interface, my Aastra VoIP phones, or infrared remotes). Next house I will probably do UPB though (specifically, Simply Automated products), simply because the switches are a lot more powerful, and their software is miles ahead of Insteon, albeit also harder to use**.
** Insteon is dumbed-down a bit to make it easier, but of course sacrifices some flexibility by doing so. My biggest gripe is you can't set up a scene that turns some things on, and others off (such as my "movie" scene does); the best workaround is to dim to 1%, which keeps my halogen pot lights still very dimly lit, and wasting power.
It depends on the power rating of the water heater. From an earlier question, I see that you live in China, so your electrical supply is 220 VAC/50 Hz. That means that the maximum power draw on a 10 A circuit is 2.2 kW (220 V * 10 A). In general, you should draw less to allow a safety margin, if the water heater uses more than about 2 kW you should get it rewired because you'll be coming close to the maximum rating of that circuit.
Note: I'm not even considering the presence of other appliances on that bathroom circuit (lights, electric razors, electric toothbrush chargers, etc.).
Based on the additional info in the question, if you only use the 1000 W and 1500 W modes on the heater, the existing wiring should be sufficient. If there's a way to prevent people from using the highest setting (like mounting the whole heater in a box where it can't be changed inadvertently), you should be OK.
Best Answer
I'm not an electrical master, but I know this: outlets catching fire is NOT normal, ever. Furthermore, the apartment manager sounds like a real weasel. Outlets only cost a few dollars - in the face of a known fire risk, why waste time claiming nothing is wrong? Just replace the suspect part. You don't need an electrician, you need a new landlord.
That said, I understand sometimes people have reasons they can't move. At the very least, you should keep a fire extinguisher handy!
First of all, you do have a problem, so don't let anyone tell you everything is fine. Get an electrician of your own in there if you have to. This is a safety issue; life has no price tag.
Now, here are some questions I can think of that will help a professional figure out your problem:
If new outlets keep catching fire after you replace them, it could be a wiring issue, not an outlet issue.
If the outlets are seeing heavy current draw, from many appliances or a few big ones, it could be that the breaker on that circuit is too big for the associated wiring. An oversized breaker would allow more current through than the wires could handle. This could cause overheating.
If the outlets seem loose (and even if they don't) it could be that the wiring inside the box, behind the outlet, is shorting out and causing sparks. I had GFI outlet that tripped all the time - I eventually discovered one of the terminals was arcing against the inside of the box.