It is located in the Val d'Illiez. It is the starting point to reach Morgins via the Val de Morgins. The name "Troistorrents" comes from the Latin "trans torrentium" which means "on the other side of the torrent". The blazon of the municipal coat of arms is "In azure with three Fir trees Vert stemmed proper, planted on three mountains of the same between which flow two mountain streams in pale Argent which fall into a third stream in fess; the mountain in the middle charged with a woman sitting, clothed Gules and holding on her knees her child dressed Argent and throwing grain Or." Troistorrents has a population () of . , 10.4% of the population are resident foreign nationals. Over the last 10 years (2000–2010 ) the population has changed at a rate of 12.7%. It has changed at a rate of 10% due to migration and at a rate of 4.2% due to births and deaths. Most of the population () speaks French (3,381 or 94.8%) as their first language, German is the second most common (90 or 2.5%) and English is the third (23 or 0.6%). There are 19 people who speak Italian and 1 person who speaks Romansh.  , the population was 50.1% male and 49.9% female. The population was made up of 1,841 Swiss men (44.4% of the population) and 236 (5.7%) non-Swiss men. There were 1,857 Swiss women (44.8%) and 209 (5.0%) non-Swiss women. Of the population in the municipality, 1,727 or about 48.4% were born in Troistorrents and lived there in 2000. There were 690 or 19.3% who were born in the same canton, while 664 or 18.6% were born somewhere else in Switzerland, and 375 or 10.5% were born outside of Switzerland.  , children and teenagers (0–19 years old) make up 26.5% of the population, while adults (20–64 years old) make up 60.6% and seniors (over 64 years old) make up 13%.  , there were 1,491 people who were single and never married in the municipality. There were 1,776 married individuals, 162 widows or widowers and 138 individuals who are divorced.  , there were 1,364 private households in the municipality, and an average of 2.5 persons per household.