It was named after the ancient city Tritaia (probably named after Triton, a son of Poseidon). Tritaia was part of the so-called dodecapolis (a union of 12 cities) . The Achaean League participated in various battles to free the region from the Macedonians.

Tritaia is described by the geographer Pausanias.

Tritaia was a municipality in the period 1835 to 1912, although not with the same villages. Prostovitsa (Drosia today) was the seat of the old municipality.

Mayors

Apostolos Vgenopoulos (1998 to 2006)

Miltiadis Gkosimidas (since 2006)

• Stavrodromi / Δ.δ. Σταυροδρομίου [ 536 ]
  
  • Stavrodromi / το Σταυροδρόμιον [ 254 ]
    
  • Xirochorion / το Ξηροχώριον [ 74 ]
    
  • Panousaiika / τα Πανουσαίικα [ 93 ]
    
  • Rachi / η Ράχη [ 115 ]
    
• Agia Varvara / Δ.δ. Αγίας Βαρβάρας [ 314 ]
  
  • Agia Varvara / η Αγία Βαρβάρα [ 210 ]
    
  • Galaros / ο Γάλαρος [ 104 ]
    
• Agia Marina / Δ.δ. Αγίας Μαρίνης [ 139 ]
  
  • Agia Marina / η Αγία Μαρίνα [ 66 ]
    
  • Kato Agia Marina / η Κάτω Αγία Μαρίνα [ 73 ]
    
• Alpochori / Δ.δ. Αλποχωρίου [ 424 ]
  
  • Agios Dimitrios / ο Άγιος Δημήτριος [ 236 ]
    
  • Alpochori / το Αλποχώρι [ 188 ]
    
• Velimachion / Δ.δ. Βελιμαχίου [ 82 ]
  
  • Velimachion / το Βελιμάχιον [ 80 ]
    
  • Moni Agion Panton / η Μονή Αγίων Πάντων [ 2 ]
    
• Drosia / Δ.δ. Δροσιάς [ 816 ]
  
  • Drosia / η Δροσιά [ 382 ]
    
  • Kato Drosia / η Κάτω Δροσιά (τ. Αγραπιδεές) [ 201 ]
    
  • Kouberion / το Κάτω Δροσιά [ 132 ]
    
  • Pteri / η Πτέρη [ 101 ]
    
• Erymantheia / Δ.δ. Ερυμανθείας -- η Ερυμάνθεια [ 370 ]
  
• Kalfas / Δ.δ. Κάλφα [ 322 ]
  
  • Kalfas / ο Κάλφας [ 273 ]
    
  • Masouraiika / τα Μασουραίικα [ 49 ]
    
• Manesion Patron / Δ.δ. Μανεσίου Πατρών [ 419 ]
  
  • Manesion / το Μανέσιον [ 138 ]
    
  • Golemion / το Γολέμιον [ 87 ]
    
  • Kato Mastrantonion / το Κάτω Μαστραντώνιον [ 148 ]
    
  • Mastrantonis / ο Μαστραντώνης [ 46 ]
    
• Roupakia / Δ.δ. Ρουπακιάς -- η Ρουπακιά [ 303 ]
  
• Skiadas / Δ.δ. Σκιαδά [ 1.036 ]
  
  • Skiadas / ο Σκιαδάς [ 573 ]
    
  • Karpeta / το Καρπέτα [ 188 ]
    
  • Moni Koimiseos Theotokou Notenon / η Μονή Κοιμήσεως Θεοτόκου Νοτενών [ 3 ]
    
  • Barakes / οι Μονή Κοιμήσεως Θεοτόκου Νοτενών [ 98 ]
    
  • Pigadia / τα Πηγάδια [ 174 ]
    
• Skouras / Δ.δ. Σκούρα [ 165 ]
  
  • Skouras / ο Πηγάδια [ 124 ]
    
  • Kardasi / το Καρδάσι [ 41 ]
    
• Spartia / Δ.δ. Σπαρτιάς [ 219 ]
  
  • Spartia / η Σπαρτιά [ 63 ]
    
  • Kyparission / το Κυπαρίσσιον [ 156 ]
    
• Chiona / Δ.δ. Χιόνας -- η Χιόνα [ 317 ]
  
  

Stadium near the village Stavrodromi

Alpochori

Alpochori "the village of Alpos", was named after the giant Alpos c 40 km from Patras. In the year 1697 and 1699 it is mentioned as Alpochori Trano, with a population of 111

From 1836 to 1841 it was a department of the municipality of Erymantheia. From 1841 to 1912 it was a department of the old municipality of Tritaia. Until the formation of the new municipality of Tritaia in 1998 it was an independent community.

Moni Agion Panton

Moni Agion Panton is a Monastery, build 1728. In 1928 only 8 Monks lived there. In 2001 the number was reduced to 2 monks. In 1928 there were 8 monks.

Drosia

Drosia is a village of the Tritaia municipality, known also in the past as Prostovitsa, at the mount Erymanthos (on a side 680 m). A Mycenean grave was found in the region.

In 1700 the village population was 156 and 673 in 1991. In the antiquity the city Eupagion was near Drosia. A Mycenean cemetery is near Drosia.

Erymantheia

Near Erymanthea there were found parts of a Mycenean wall.

Kalfa

Kalfa is a village c. 45 km SW from Patra. It is near the border of Achaia with Ilia. In the past it was a community, now part of Tritaia

Spartia

Spartia is a mountain village c. 50 km from Patras.