The central company hospital of Ajer Tawar was founded in 1918 and is mentioned by E. van de Velde (Het Ziekenhuis, nrs. 9, 10 and 11 (1940). It was one of the 33 central company hospitals on the Eastcoast of Sumatra. It was also mentioned by B.M. van Driel, company doctor of the Tobacco Company Arendsburg at Soengei Sengkol in the publication Mededeelingen van het Pathologisch Laboratorium te Medan (1930), Mortality rates and causes of death among 318071 estate labourers in Sumatra in 1929. Table 1b mentions for the hospital Ajer Tawar 2,243 indentured labourers, of whom 12 died (5.35 %).
Ajer Tawar is part of the district Tandjong Pura with a capital town of the same name, which is situated in the department Langkat and the subdepartment Beneden Langkat in the Gouvernement Oostkust van Sumatra (Gonggryp 1934, 1383)