Laboratory water is a fundamental resource in applied biology, critical for preparing reagents, cleaning equipment, and conducting experiments that require high levels of purity and consistency. In Kenyan laboratories, ensuring the quality of water used directly influences the reliability of biological assays and research outcomes. Understanding the sources of water available and their characteristics helps professionals select appropriate water types and treat them suitably to meet laboratory standards.

2.1 Sources of Water

Water sources vary in quality, availability, and suitability for laboratory use in Kenya. Applied biology laboratories commonly rely on municipal water supplies, boreholes, rainwater, and natural surface waters, each presenting unique benefits and challenges. Knowledge of these sources allows laboratory managers to implement effective water treatment strategies to ensure that water meets the required purity for biological applications.

2.1.1 Municipal Water Supply

Municipal water supply is the most accessible source for many laboratories situated within urban and peri-urban areas in Kenya. This water is treated by local authorities such as Nairobi City Water and Sewerage Company to meet national potable water standards before distribution.

Characteristics of Municipal Water Supply

• Regulated Quality: Municipal water undergoes treatment processes including coagulation, sedimentation, filtration, and chlorination to reduce microbial and chemical contaminants.
• Variable Consistency: Despite treatment, water quality can fluctuate due to aging infrastructure, intermittent supply, and contamination during distribution.
• Chlorine Residuals: Chlorination provides disinfection but residual chlorine can interfere with sensitive biological assays if not removed.
• Availability: Generally reliable in major towns but may be inconsistent in remote or informal settlements.
• Cost Implications: Municipal water is relatively affordable but laboratory-grade water may require additional purification, increasing operational costs.

Laboratories in institutions such as the Kenya Medical Research Institute (KEMRI) depend on municipal water but often incorporate further purification steps like reverse osmosis or distillation to achieve laboratory-grade water.

2.1.2 Borehole Water

Borehole water is extracted from underground aquifers via drilled wells and is a common alternative in both rural and urban Kenyan settings where municipal water is unavailable or unreliable.

Characteristics of Borehole Water

• Variable Mineral Content: Groundwater often contains dissolved minerals such as calcium, magnesium, and iron, which can affect water hardness and suitability for laboratory use.
• Microbial Contamination Risk: Without proper sealing and maintenance, boreholes may be vulnerable to microbial contamination from surface runoff.
• Stable Supply: Boreholes typically provide a more consistent supply compared to surface water sources, especially during dry seasons.
• Treatment Requirements: Often requires filtration, softening, and disinfection before use in laboratories.
• Cost and Infrastructure: Installation and maintenance of boreholes involve significant investment but can reduce dependence on external water suppliers.

2.1.3 Surface Water

Surface water includes rivers, lakes, and reservoirs and is an important source in regions where other water supplies are limited. In Kenya, institutions near Lake Victoria or the Tana River basin may access surface water.

Characteristics of Surface Water

• High Contamination Potential: Surface water is susceptible to contamination by pathogens, organic matter, and industrial pollutants, requiring rigorous treatment.
• Seasonal Variability: Water quality and availability can vary significantly with rainfall patterns and human activities.
• Turbidity and Solids: High levels of suspended solids necessitate pre-treatment such as sedimentation and filtration.
• Complex Treatment Needs: Often requires multiple purification stages including coagulation, filtration, and disinfection to be laboratory-appropriate.
• Environmental Impact Considerations: Withdrawal must comply with environmental regulations to protect ecosystems and downstream users.

County government laboratories in Kisumu, for instance, source water from Lake Victoria but implement advanced purification systems to meet laboratory standards.

2.1.4 Rainwater Harvesting

Rainwater harvesting captures precipitation from roofs and other surfaces, providing an alternative water source for laboratories, particularly in remote or off-grid areas.

Characteristics of Rainwater Harvesting

• Low Mineral Content: Rainwater is naturally soft and free from dissolved minerals, making it ideal for purification to laboratory-grade water.
• Contamination Risks: Collection systems can introduce microbial contamination; proper maintenance and first-flush diversion systems are essential.
• Seasonal Dependence: Availability depends on rainfall patterns, which in Kenya vary with bimodal and unimodal rainy seasons.
• Storage and Treatment Needs: Requires clean storage tanks and treatment such as filtration and UV disinfection before laboratory use.
• Cost-Effectiveness: Low operational costs after installation make it attractive for institutions with limited budgets, such as rural health clinics.

Chapter Summary

This chapter explored the various sources of water commonly used in laboratory settings, emphasizing the importance of selecting appropriate water quality for different experimental needs. It then examined several methods of water treatment essential for ensuring purity and suitability in laboratory applications. Distillation was discussed as a process that removes impurities through boiling and condensation, producing highly pure water. Deionization was explained as a technique that eliminates ionic contaminants by exchanging ions, critical for sensitive analytical procedures. Filtration and sedimentation were described as physical methods to remove particulate matter, with filtration using membranes or filters and sedimentation relying on gravity to separate solids. Reverse osmosis was presented as a membrane-based process that effectively removes dissolved substances by applying pressure. Finally, adsorption was covered as a method that uses materials like activated carbon to remove organic compounds and chlorine, improving water taste and safety for laboratory use.