Ruri Prihatini Lubis and Muheri Indra Aja Nasution 2026. Analysis of the Effect of Using a Natural Water Filter on the Efficiency of Household Expenditure and Customer Satisfaction at Perumda Tirtanadi in Hamparan Perak Sub-District . Jurnal Teknik Indonesia. 5, 01 (Jun. 2026), 118–128. DOI:https://doi.org/10.58471/ju-ti.v5i01.1013.