Usually from people taking showers whilst covered in sand.
Radio Shack "drain pipe tracer".
sand or some other type of abrasive mat in water supply,
Foul Air
Yes, a sewage drain pipe can be too large.
If you are talking about a roof water drain pipe to sewer it is illegal. If you are talking about a sink drain pipe well that is where they all connect to so yea.
dvw pipe = drain, waste and vent pipe.
As long as the pipe going into the wall is straight, the rest of the drain pipe can be routed however it needs to be. Very often the trap is at an angle to the pipe in the wall.
I have no idea sorry it's never happend to me before. Maybe it found its way up a drain pipe :-)
There are multiple reasons to get your drain pipe inspected. One major reason to inspect a drain pipe is before buying a house to make sure everything runs correctly.
sand
You can drain it directly into a drain pipe. Just make sure the the top of the drain pipe is even with the top of the washing machine. If not, the water from the washing machine will drain all of the time. There is no valve in the machine to stop the water from draining. The washing machine drains using a pump motor.
Probably leaky drain pipe form toilet which passes through that room. Work out which corner of that room is below the toilet, you will probably see a swelling in the wall where the drain pipe is hidden. Call a plumber and get him to fix it.