Timothy Purvis

Lead (Pb) exposure through drinking water causes a substantive preventable disease burden. The primary source of Pb in drinking water is through Pb-containing infrastructure, including leaded-brass fittings, galvanized iron/steel pipes, and some plastics. As the source of Pb through drinking water is widely known, its prevention through a supply chain intervention is possible. This is true in Uganda, where the use of potentially Pb-containing handpumps and piped drinking water infrastructure has been previously documented. As Uganda has signed the Global Lead-Free Water Pledge and appears to import Pb-containing materials, an evaluation of its supply chains for drinking water infrastructure may identify points of future intervention. We used an established desk-based methodology to produce Supply Chain Maps (SCMs) of major infrastructure components, including handpumps, submersible pumps, and pipes. We collected information from drinking water infrastructure vendors, installers, manufacturers, and relevant press statements through searches from October 2024 to April 2025. We identified a diverse set of handpump manufacturers (n=25) in South Asia, from which evidence indicates that Pb-containing galvanized iron/steel infrastructure is entering Uganda. We found a smaller set of firms responsible for producing handpumps and submersible mechanized pumps (n=8), for which materials are advertised as Pb-free stainless steel. However, this claim lacks third-party validation in many cases. If true, this indicates the existence of available Pb-free alternatives, suggesting that future installation of Pb-containing materials can be avoided. We did not find evidence of a domestic manufacturing base for handpumps in Uganda, suggesting that the import process may be a critical control point for Pb elimination. There was limited information about the pipes and fittings used in drinking water systems, as the processes governing this infrastructure are decentralized and appear to lack an online presence. We present the potential for leveraging the outputs of SCMs to inform other tools, like the Hazards Analysis and Critical Control Points (HACCP) framework for protecting national drinking water supply chains, and the Water Safety Plan (WSP) tool for ensuring Pb-free local water systems. From the findings of the Uganda SCM, we identified potential intervention points to be further evaluated through HACCP and WSP frameworks. This study demonstrates that even in the absence of direct material testing, supply chain structures can identify plausible entry points and controls for toxic materials in drinking water infrastructure.

Low-cost, scalable tests hold great potential to increase the availability of water safety data globally, especially in resource-limited settings. We evaluated the Lishtot TestDrop Pro, a commercially available, low-cost triboelectric-based sensor marketed for real-time determination of water contamination, including microbiological safety. We prepared a total of 199 water samples by serial dilution of raw wastewater influent into deionized water to produce a range of E. coli counts from 300 per dilution plate) CFU/100 mL to evaluate the sensor. We tested these waters using the manufacturer’s instructions. We collected sensor readings using three settings on each of five devices, generating nearly 8,955 individual measurements to compare against E. coli measured via standard membrane filtration assays (EPA Method 1604), a common metric of drinking water safety. We found no statistical correlation between the sensor score and E. coli presence in water: 43% of sensor readings indicated “safe” when wastewater and E. coli was present, and 56% of samples lacking E. coli were deemed “unsafe” by the sensor when wastewater was absent. The Lishtot TestDrop Pro is not an accurate method for measuring microbiological water safety.

Toxic metals and metalloids (TMs) are inorganic chemical contaminants that cause adverse health outcomes. Drinking water is an important exposure route for TMs such as arsenic (As), cadmium (Cd), lead (Pb), and manganese (Mn). Arsenic and manganese are geogenic contaminants that can also arise from localized anthropogenic and industrial sources. Lead leaching from Pb-containing pipes and fittings is of particular concern. Occurrence of these and other TMs has been reported in drinking water in Mexico, but the evidence has not been synthesized. Following PRISMA Guidelines, we conducted a systematic review to understand the distribution of TM occurrence in Mexican drinking water. We searched PubMed, EBSCO Global Health, and Web of Science to identify studies published in English after 1968 that measured any TM in drinking water globally, identifying a set of 20,052 papers for screening, last searched in March 2025. A total of 134 papers were included that report quantitative data on TMs in Mexican drinking water. We found that 62%, 20%, 14%, and 18% of Mexican drinking water samples exceeded the World Health Organization’s Guideline Values for As, Pb, Mn, and Cd, respectively. Overall, there is sufficient evidence to recommend preventive measures to reduce TM exposures from drinking water in Mexico, but there is insufficient data to inform targeted remediation efforts. Across Pb, Mn, and Cd, we found that sample sites were overwhelmingly in urban settings, leaving rural populations underrepresented. While arsenic is well characterized across the country and should certainly be addressed, we found that Pb, Mn, and Cd are understudied outside of the region surrounding Mexico City. We have developed a GIS layer for researchers to identify areas where research has not been conducted. This study can inform the efforts of public health practitioners, policy-makers, and researchers to identify understudied regions for further monitoring, surveillance, and review.

Lead (Pb) is a neurotoxin with no known safe level of exposure. Widespread lead contamination has been reported in rural groundwater-supplied drinking water systems in low- and middle-income countries (LMICs), primarily arising from the corrosion of lead-containing plumbing materials such as galvanized steel and leaded brass. The National Sanitation Foundation (NSF) 372 standard certifies drinking water system components as “lead-free” when the lead content is below 0.25% by weight for wetted surfaces. NSF 61 standard, in contrast, certifies the safety of “endpoint” drinking water system components based on their potential to leach chemical contaminants, including lead. This study evaluates the lead content (NSF 372) and lead leaching behavior (NSF 61) of plumbing components commonly used in LMIC rural community water systems to determine their suitability for delivering safe drinking water. Galvanized borehole handpump tanks (specifically, spouts) and brass taps widely used in Ghana and other LMICs were tested alongside stainless-steel alternatives and lead-free PVC pipe controls against NSF 61 and NSF 372 standards. Stainless-steel components and PVC controls met both standards, whereas galvanized steel spouts and leaded brass taps did not. Average water lead levels leached over the 19-day experimental period were 192 µg/L (SD = 89) for leaded brass taps, 34 µg/L (SD = 3) for galvanized steel spouts, 0.4 µg/L (SD = 0.1) for stainless-steel taps, 0.3 µg/L (SD = 0.3) for PVC pipes, and below the detection limit (0.5 µg/L) for stainless-steel spouts. These findings indicate that lead-containing galvanized steel and leaded brass components that exceed NSF 372 and/or NSF 61 standards pose a significant health risk and should not be used in potable water systems. Lead-free alternatives that meet NSF 372 and NSF 61 standards, such as stainless steel, are strongly recommended for safer rural water infrastructure due to their minimal lead-leaching risk.

Toxic metals (TMs) harm human health, causing cancers, irreversible neurocognitive impairment, and cardiovascular disease. Drinking water is an important source of exposure to TMs. However, current peer-reviewed literature does not adequately capture or synthesize the extent of TM occurrence in drinking water in East Africa. The goal of this systematic review is to report and synthesize available evidence on the occurrence of TMs in drinking water across the region. A global systematic review of TMs in drinking water was recently conducted by Fisher et al., and data from East Africa were used for this analysis. A search of studies from PubMed, EBSCO Global Health, and Web of Science was conducted in 2019, with a search update in March 2025. We included studies published in English after 1968 that included a primary measurement of at least one TM of interest in drinking water in the region. In total, 111 studies (of the 3,993 reported in the larger systematic review) met these criteria. Among TMs of health concern, sufficient East African observations were available for Arsenic, Lead, and Manganese, making these the focus of this regional review. For each metal, average concentrations and the percentage of observations exceeding World Health Organization Guideline Values were calculated, with further analysis of observations by Urban and Rural and by Joint Monitoring Programme Improved and Unimproved categorization. 24%, 17%, and 31% of observations of Arsenic, Lead, and Manganese exceeded their respective WHO Guideline Values. Additionally, many urban centers and large portions of the region were geographically underrepresented in the literature. The synthesized data are sufficient to recommend primary prevention and progressive remediation efforts to prevent and minimize exposure to TMs in drinking water across East Africa. Nevertheless, substantive literature gaps remain, indicating a need for further research across much of the region.

Toxic metals (TMs) are metallic contaminants that cause adverse health effects even at low exposure levels. Arsenic (As), Manganese (Mn), Lead (Pb), and Cadmium (Cd) are among these contaminants of concern, causing irreversible developmental damage to children (Pb), as well as cardiovascular disease (Pb) and cancers (As) in adults. Arsenic and Manganese are primarily geogenic groundwater contaminants that can also be introduced to drinking water systems by localized anthropogenic contamination sources. Corrosion of lead-containing plumbing components contributes to much of the Lead in drinking water, while localized anthropogenic pollution can leach into some otherwise clean water sources as well. Cadmium is often used in fertilizers and can be an indicator of anthropogenic contamination. We reviewed published studies reporting on concentrations of As, Mn, Pb, and Cd in Ghanaian drinking water quality to assess the occurrence and potential health implications of these TMs. As part of a larger systematic review, we searched for peer-reviewed literature from PubMed, EBSCO Global Health, and the Web of Science, between November 2019 and March 17, 2025, to retrieve studies published in English after 1968 that assessed toxic metals levels or contamination in drinking water in Low- and Middle-Income Countries. This generated 20,552 studies from the initial search, which were screened down to 3,993 studies for extraction. We selected the 93 studies that measured a TM in Ghanaian drinking water for full-text review and data extraction. We focused on Arsenic, Manganese, Lead, and Cadmium, for which we had the most data on metals with WHO limits. 79 studies reported concentrations of Arsenic, Manganese, Lead, and/or Cadmium. A quality evaluation was carried out for these studies by assessing the suitability of reported sample collection, analysis, and quality assurance/quality control practices, and by extracting information on the source of drinking water, GPS coordinates, and observed concentrations for each TM. This resulted in the inclusion of 93 studies comprising 82,111 samples, with 8,124, 11,882, 6,079, and 6,679 observations for Arsenic, Manganese, Lead, and Manganese, respectively. We found that 18%, 34%, 17%, and 15% of included Ghanaian drinking water samples exceeded the WHO Guideline Values for Arsenic, Manganese, Lead, and Cadmium, respectively. Data were widespread across Ghana, though we found few studies in the regions north of Kumasi. These findings comprise sufficient evidence to recommend preventative action to eliminate such contamination in new drinking water systems in Ghana, as well as to explore potential interventions to progressively prioritize and remediate the most serious existing exposures to TMs in existing drinking water systems.

Low-cost technologies are increasingly being explored and marketed as capable of filling gaps in global water quality monitoring (WQM), especially in resource-limited settings. This study evaluates a commercially available, low-cost triboelectric-based sensor that is marketed for real-time detection of E. coli in drinking and environmental waters. A result of 0 indicates contaminated water, whereas a result of 99 indicates “safe” water. A total of 199 water samples were prepared by serial dilution of raw wastewater influent into deionized water to produce a range of E. coli concentrations from 100 CFU/100 mL in evaluating the triboelectric sensor. Sensor readings were collected using three settings on each of five devices, generating nearly 9,000 individual readings to compare against Membrane Filtration taken in triplicate as the true E. coli concentration. Spearman’s rank correlation revealed no statistical significance between the sensor score and E. coli concentrations (ρ = -0.1493, p = 0.0603). When sensor readings were taken in aggregate, a moderate predictive capacity was observed as a presence/absence classification (AUC = 0.77), though this requires 15 measurements per sample, which is beyond the guidelines of the technology. The sensor frequently misclassified both known-negative and known-positive samples, with a high rate (64%) of score clustering at the extremes (0 or 99). These findings indicate that the sensor in its current form is not suitable for public health evaluation of microbial contamination in drinking water. The lack of predictive ability, which contradicts the marketed capacities and user expectations, is likely not unique to the evaluated sensor. This study highlights the importance of rigorous validation of novel WQM technologies before deployment to identify the appropriate application of sensors, which may remain beneficial, even if not for immediate public health use.

Lead (Pb) in drinking water causes organ damage, cardiovascular disease, cancers, and lifelong neurological and developmental impairment, disproportionately harming infants and developing fetuses. However, evidence on lead in drinking water in low- and middle-income countries (LMICs) is limited and lacks robust synthesis, impeding action. We conducted a systematic review and meta-analysis of peer-reviewed studies reporting lead in drinking water in LMICs, according to PRISMA guidelines. We searched PubMed, Scopus, and Web of Science for studies published in English since 1969 reporting lead concentrations in drinking water. Study relevance was ranked using supervised clustering and machine learning. Relevant studies were manually screened for inclusion; data were manually extracted from included studies. Within-study risk of bias was scored using quality items defined in this work. Between-study bias was assessed based on continuity and symmetry of the (roughly lognormal) distribution of data included in the review. Of approximately 40,000 search results (for both lead and other TMs), 16,868 scored relevant using a trained machine learning algorithm; of these, 3,187 met inclusion criteria. Approximately one third (n=1,088) reported on lead. Central and Southern Asia accounted for 45% of included datasets, while 31% of LMICs were unrepresented. Many studies (45%) had sites purposively selected for known or suspected contamination; after excluding such “targeted” studies, metaregression indicated that >20% (95% CI: 20-27%) of samples exceeded World Health Organization (WHO) guideline values for lead (n=523). Potential sources of bias within studies include sample collection and analysis limitations (lower quality studies) and purposive site selection (“targeted” studies); potential sources of bias among studies include language limitations, exclusion of grey literature, geographic heterogeneity of datasets, and potential publication bias. This work suggests that lead contaminates drinking water at levels of health concern in LMICs worldwide, and that increased collective efforts to prevent, manage, and monitor such contamination are merited.

Lead (Pb) is a neurotoxin with no known safe level of exposure. Widespread lead contamination has been found in rural groundwater-supplied drinking water systems in low- and middle-income countries, potentially from corrosion of lead-containing materials such as galvanized steel and brass. National Sanitation Foundation (NSF) 61 is an international standard for certifying the safety of water system components in contact with drinking water based on their capacity to leach chemical contaminants, especially lead, into drinking water. Another standard, NSF 372, certifies the material composition of drinking water system components as ’lead-free' if lead content is ≤0.25% by weight for wetted surfaces. This work investigates the lead leaching potential of components frequently used in these systems and explores potential alternatives to determine which components can be safely used in drinking water systems. Galvanized handpump spouts and leaded brass taps of types widely used in rural water systems in Ghana and stainless-steel alternatives, were tested against NSF 61 and NSF 372 standards. Lead-free PVC pipe segments were used as controls. Test results indicated that all stainless-steel components and PVC controls met NSF 61 and NSF 372 standards while galvanized spouts and brass taps did not meet either. The average lead levels leached over the experiment period from the brass taps, galvanized spout, stainless-steel taps, PVC pipes, and stainless-steel spouts were 192 (SD=89), 34 (SD=3), 0.3 (SD=0.1), 0.2 (SD=0.3), and 0.1 (SD=0.1) µg/L, respectively. Overall, the use of lead-containing galvanized handpump spouts and brass taps should be avoided in water systems due to their lead leaching potential; alternative products made from lead-free materials such as stainless steel should be substituted.