What Chemicals are in the Drinking Water of Lira District, Uganda?

Surveyed March 2024

Background

Globally, microbial drinking water quality remains a top health concern in low- and middle-income countries. Heavy metals in the water in Lira, including chemicals like fluoride, arsenic, and nitrates are also a growing concern, with evidence of widespread which may be present in drinking water. Further, growing evidence indicates widespread lead contamination in drinking water supplies, often being introduced through lead-containing water system components.

The Aquaya Institute is monitoring microbial water quality over time in two districts in Uganda (see prior research briefs). In March 2024, Aquaya also tested chemical water parameters at a subset of water points to get a more comprehensive picture of water quality, including contaminants with known health risks and physiochemical parameters affecting user acceptability.

A handpump at a school in the Lira District, Uganda.

Aquaya visited 61 institutions, which were randomly selected among all public schools and healthcare facilities in Lira. We identified 79 drinking water points at these institutions – including both primary and secondary sources. Ten (13%) were unavailable for testing due to breakdown or other reasons. We collected drinking water samples from the remaining 69 water points – 53 at schools and 16 at healthcare facilities. A subset of these samples was analyzed for different water quality parameters.

Results

Parameters with low health implications

Most samples (93%) had pH below the Uganda National Bureau of Standards (UNBS) minimum requirement of 6.5, and one-third of samples (32%) had chloride levels above the standard of 250 mg/L; acidic water and elevated chloride may cause corrosion of metal parts in the water system. A quarter of samples (25%) had turbidity above the standard of 5 NTU, which may reduce chlorine’s treatment effectiveness and may be visually unpleasant to water consumers. Three-fifth of samples (62%) had iron levels above the standard of 0.3 mg/L, and one-third of samples (32%) had phosphate levels above the standard of 2.2 mg/L. Elevated iron and chloride do not represent a known health risk, but water consumers may not like the water’s taste or appearance.

All samples had electrical conductivity, total hardness, and sulfate within the standard range.

Parameters with high health implications

We analyzed a set of chemicals (fluoride, nitrate, and nitrite) and heavy metals (arsenic and lead) with known negative health impacts. Fluoride and arsenic were included due to their recognition as priority chemicals by the international WHO/UNICEF Joint Monitoring Programme, nitrogen (nitrate and nitrite) was included due to its persistence in rural areas, and lead was included due to national and global interest to reduce lead exposure from drinking water.

All samples met the UNBS drinking water standard for fluoride and nitrates. Few samples had arsenic (3%) concentrations above the UNBS standard.

Overall, 10% of samples had detectable lead levels above 15 μg/L, or 15 parts per billion (ppb). Due to the severe health impacts of lead exposure, we include more information about lead in the following section.

Spotlight: Lead in drinking water

In some cases, lead is present in drinking water from naturally-occurring sources. However, in most cases, lead contamination in drinking water comes from lead-containing components in water systems, such as pipes, faucets, and handpump components. Exposure to lead in drinking water may lead to negative neurodevelopment effects, with infants and children being most vulnerable.

There is no safe level of lead in drinking water. In this brief, we define detectable lead as above 15 µg/L (ppb) due to the reporting limit of the analytical method used (ICP-OES, USEPA Method 200.2). This is less conservative than the maximum level allowed by the UNBS drinking water standard and the WHO provisional guideline value of 10 ppb. In other words, it is possible that more samples exceeded the 10 ppb standard than the percentage with detectable lead reported here.

One-tenth (10%) of drinking water samples had detectable lead (≥15 ppb), including 11% of school samples and 6% of healthcare facility samples. All samples with detectable lead were taken from handpumps; no lead was detected in samples from piped taps or springs (Figure 1).

All samples with detectable lead had pH below 6.5; however there were few samples with pH above 6.5. Low pH promotes corrosion of water system components, which can release metals into the water, including lead if present.

Random daytime Samples, Lira: Lead concentrations by water point type. Water samples were collected during the daytime from a sample of institutional water points in Lira District.

Summary

^{This work (WaterTRACS) is supported by funding from the Conrad N. Hilton Foundation.}