Background: Gravity feed system (GFS) is a downstream distribution system powered by gravitational force to households, and is commonly used by hilly-area populations, including Aboriginal (Orang Asli) communities, as they cannot be provided with acentralized water supply system. One of the health problems related to exposure to level of nitrate (NO3-) in drinking water above the maximum contaminant level (MCL) is neonatal methemoglobinemia, also known as blue baby syndrome. This study aimed to
asses the health risk due to exposure to nitrate in gravity feed system water in an
Aboriginal (Orang Asli) village near Rembau, Negeri Sembilan, Malaysia. Subject and Method: This cross-sectional study was carried out in August 2022 involving 48 study subjects selected purposively Subjects with a filtration system installed in their houses were excluded. The independent variable was nitrate in GFSwater. The dependent variable was health risk. A questionnaire was used to obtain socio-
demographic data. Water samples were analyzed using a HANNA Instruments multi-
meter with an attached nitrate electrode. All data collected were analyzed using SPSS

Version 22. Descriptive statistics, including mean, median, and standard deviation, were
used to summarize the physicochemical characteristic of drinking water.
Results: Nitrate in samples did not exceed the maximum contaminant level (MCL) of
45 mg/L set by health authorities. Readings ranged from 2.15 to 7.65 mg/L (Mean=4.99;
SD=1.37). Calculation of Hazard Quotient (HQ) found that all respondents have an HQ
of less than 1, indicating no carcinogenic risk to consumers.
Conclusion: Nitrate levels found in this study are below the level of concern, and
adverse health effects are unlikely to occur under current exposure conditions. However,
it is recommended to conduct assessments on a regular basis to ensure that they do not
bring harm to public health.