Water mites (Parasitengonina: Hydrachnidia) represent the most diverse group of aquatic arachnids, comprising more than 7,500 described species distributed across over 480 genera and 55 families. The Neotropical region harbors the highest known diversity of the group, with approximately 165 recorded genera. Despite this, Brazil, which is considered the most biodiverse country in the world, still presents a significant gap in the taxonomic knowledge of these organisms. This study provides a historical overview of Hydrachnidia species descriptions in Brazil, present an updated survey of the number of species recorded in the country, and introduce the Acarological Collection of the Center of Taxonomical Collections of Universidade Federal de Minas Gerais (CCT- UFMG), currently the largest collection of this group in Brazil. We reviewed taxonomical descriptions of Hydrachnidia in Brazil. In parallel, most of the specimens deposited in the Acarological Collection also were examined. The collection was established in 2011 and contains material obtained from research activities conducted by the UFMG Acarology Laboratory, as well as specimens deposited by other institutions. Most Brazilian water mite species were described by foreign researchers throughout the twentieth century. Many of these descriptions are brief and based solely on adult stages, which cannot be readily associated with their parasitic larvae. Additionally, most holotypes and paratypes were deposited in collections abroad. Historically, research efforts have been concentrated in southern Brazil and in the states of Rio de Janeiro and Amazonas, leaving significant taxonomic gaps in the Southeast, Midwest, and Northeast regions. Over time, research activity on the group gradually declined, resulting in a gap of nearly three decades beginning in the 1980s. Since 2020, however, studies on Brazilian water mites have resumed and are now, for the first time, being conducted predominantly by Brazilian researchers. Our survey identified slightly more than 700 species described from Brazilian territory. The Acarological Collection, currently houses more than 1000 water mites specimens from all continents except for Antarctica, most of which originate from regions of Brazil that remain largely unexplored for water mites. Currently, it comprises representatives of 36 genera of Brazilian water mites, making it the largest collection of the group in the country.