The town is named after the Muvattupuzha river (Muvattupuzha Aaru) which flows through it. The name is made up of three Malayalam words: 'Moonnu', which stands for 'three', 'aaru' - small river, and 'puzha', which also means river. 'Aaru' is a word that is usually used for rivers in the southern half of Kerala, while the term 'puzha' is used in the northern parts. The three rivers in this case are the Kothamangalam river or Kothayaar, Kaliyar and Thodupuzha aaru, which merge to form a single river. This place is called 'Thriveni Sangamam' in Malayalam which means `the point of confluence of three rivers'. Muvattupuzha river was practically free from pollution which slowly is changing due to the growth of small towns on the river's banks as well as industrial endeavours.
Muvattupuzha river (Malayalam: മൂവാറ്റുപുഴയാര്) which starts and flows through Muvattupuzha town runs for 121 km and enters Kottayam district as well. The major source of water is the Thodupuzha river which starts in the Idukki district and provides water throughout the year, enabled by the supply of water from Idukki arch dam. Idukki Dam is the largest arch dam in India and it is used for hydro-electric power generation. this is an old heritage route all along the river's path up to Vaikom. Old settlements along the path of the river evolved into towns along the Muvattupuzhayaar flow. be it Vaikom, Piravom, Muvattupuzha. ancient times transportation was essentially through Kettuvallam(Country boat) travelling to Vettikkattumukku and Vaikom to reach Alappuzha and Kochi.
Before Kothamangalam and Thodupuzha evolved as prominent hill produce market, Muvattupuzha was the old centre owing to the connectivity through the river. Muvattupuzha river is the prime victim of river pollution nowadays. Green People, an environmental organization is now leading a campaign to save the Muvattupuzha river.Companies like Hindusthan Newsprint Limited functions near the banks of this river but this company was having advanced effluent treatment system but these days this system is not functioning as per expectation and the river water turns black where effluent joins river at pipeline junction.