A flush toilet is a toilet that disposes of human waste by collecting it in a bowl and then using the force of water to channel it through a drainpipe to another location for treatment, either nearby or at a communal facility. Flush toilets can be designed for sitting or squatting. Most modern sewage treatment systems are also designed to process specially designed toilet paper, and there is increasing interest for flushable wet wipes. Porcelain is a popular material for these toilets, although public or institutional ones may be made of metal or other materials.