Depends on the design, but I suspect you set the seat height to the correct position and work from that, not use the waste as a height guide.
None. It is the same as a normal toilet, 3" or 4" drain.
An RV toilet is designed to be mounted over a holding tank. They use almost no water which at first might sound appealing, but unless you have a septic tank under your bathroom it would be bad news for home installation. Unless modified, an RV toilet would not be able to get the solid waste to your home septic system. A home toilet uses the force of the water to move the solid waste to your septic tank. Look for a low flush toilet or a composting toilet instead.
The flush toiletThe flush toilet, the most common type of toilet found, sends waste through a series of pipes that lead to a sewer system and eventually a waste treatment plant or septic tank.Squat ToiletCommon in Turkish and Japanese households, this toilet looks like a porcelain hole in the floor that individuals have to hover over, with their knees bent in a squat position.UrinalsThis is the type of toilet commonly seen in men's restrooms. It is mounted against the wall and can be a single or a communal urinal.Incinerating ToiletThis is a waterless type of toilet. Instead of using water to flush away waste, it burns excrement and other waste products.Composting ToiletThis type of toilet composts human waste by removing moisture from excrement.Outhouse or Pit ToiletCommonly found at campgrounds or in extremely rural areas, this is a hole dug in the ground with a small structure built around it.PHS
A toilet is used for getting rid of body waste.
The laundry waste pipe is fitted to the main drain near the toilet and the main pipe down the line past toilet is partly plugged, forcing the laundry waste up the toilet waste tube. You need to auger the pipe from toilet to outside. If all the piping is in ground you will have to remove toilet from floor to do this properly.
The problem of having waste accumulating in the toilet.
Only human waste and toilet paper. NOTHING else.
There is a blockage in the waste line. Have you flushed the basement toilet to see what happens? Try running the upstairs shower and see what happens. (use two persons , one up stairs, one downstairs so you can control the amount of water that rises in the toilet.) There should be a "clean out" cap somewhere downstairs near the point where the waste line exits the house. It is here that one would "snake" the line. The other possibility is the water level in the downstairs toilet is lower than the level of the waste line exit. This means that the point of exit of the line is physically higher than the toilet. The only remedy for this is to raise the toilet to above the height or replumb the toilet into a waste pump that evacuates upwards to a point slightly higher than the waste line. This is the most common set-up in a "basement" toilet. The toilet evacuates into a point lower than the floor. The waste pump or grinder pump then pumps the waste upwards than gravity allows it to evacuate normally. The benefit is that the waste pump creates a separate system for the basement toilet. Y-THINK-Y
Flush it down the toilet, or you can throw it out.
Water and waste
Most people recommend getting a toilet that does not have splashback in order to prevent a person's waste and waste filled water from splashing on them when they use the toilet.
There are special toilets designed just for this reason. They have holding tanks built into them with pumps to pump the waste up to the level of the sewer lines.