Selection of a Water Purification System for the Laboratory: Key Factors and Recommendations

In a laboratory environment, water quality plays a crucial role in conducting analytical methods, preparing chemical solutions, and ensuring the accuracy and reproducibility of experiments. Even minimal contamination can negatively impact analytical results, making it essential to ensure an appropriate level of water purity. 

Modern laboratory applications require different levels of water purification depending on the specific process requirements, and the choice of a suitable system depends on several factors, including the quality of the feed water, the required purity, the technological solution, and operational costs. This article focuses on the key aspects to consider when selecting a laboratory water purification system.

Required Water Quality 

When selecting a water purification system, it is essential to determine the required water quality according to its intended use: 

• Type I (ultrapure water) – suitable for sensitive analytical methods such as HPLC, ICP-MS, or PCR. 
• Type II (pure water) – used for buffer preparation, culture media, or clinical applications. 
• Type III (technical water) – suitable for washing laboratory glassware, autoclaves, or other technical applications. 

View the Watrex Praha Water System Catalog. 

Feed Water Quality 

Before selecting a system, it is advisable to analyze the feed water, which may come from the municipal water supply or pre-treated sources, to allow the supplier to recommend the most suitable system for your needs. Parameters such as ion content, organic substances, and microbial contamination can influence the suitability of a specific system. 

Purification Technologies 

Modern water purification systems combine several technologies to achieve the required purity: 

• Filtration – mechanical filtration is the first step in the purification process, removing solid particles such as sediments, rust, and other mechanical impurities. Filters with different pore sizes (e.g., 5 μm or 0.2 μm) are used depending on the required water purity. 
• Activated Carbon – this step removes chlorine, organic contaminants, and certain volatile organic compounds (VOCs). Activated carbon absorbs chemicals that could affect analytical methods or cause unwanted reactions. 
• Reverse Osmosis (RO) – one of the most effective methods for removing dissolved salts, heavy metals, bacteria, and most organic impurities. This technology uses a semi-permeable membrane that allows water to pass through while retaining most contaminants, significantly reducing water conductivity. 

Watrex img.2: Reverse osmosis filter connection scheme.

• Deionization (DI) – this method uses ion exchange resins to replace cations (e.g., Ca²⁺, Mg²⁺, Na⁺) and anions (e.g., Cl⁻, SO₄²⁻) with hydrogen (H⁺) and hydroxide (OH⁻) ions, resulting in nearly ion-free water. This technology is essential for producing ultrapure water. 
• Ultraviolet (UV) Radiation – used for water disinfection and organic matter breakdown. UV radiation at a wavelength of 185 nm effectively reduces total organic carbon (TOC) content, while UV at 254 nm is used for bacterial and viral inactivation. 
• Ultrafiltration (UF) – this technology utilizes membranes with pore sizes smaller than 0.01 μm, effectively removing bacteria, endotoxins, pyrogens, and other biological contaminants. It is essential in applications requiring the elimination of biological contamination, such as buffer preparation for cell cultures. 
• Electrodeionization (EDI) – an advanced technology combining ion exchange resins with an electrochemical regenerator, enabling continuous operation without chemical regeneration. The result is water with exceptionally low conductivity and minimal contamination. 

Watrex img.3: Types of purification technologies.

The choice of the right combination of these technologies depends on the required water purity and its laboratory application. 

Capacity and Flow Rate 

The system selection should match the laboratory's daily water consumption. For example, small laboratories may require 10–50 L/day, while large research facilities may need hundreds of liters per day. The system's flow rate should be sufficient for efficient operation and rapid container filling. 

Maintenance, Service, and Supplier Selection 

When selecting a system, it is important to consider operating costs, including filter replacement, resin exchange, and other components. Regular maintenance is essential for maintaining optimal functionality and water quality. 

In addition to technical parameters, the availability of spare parts and manufacturer service support should also be considered. Reputable suppliers typically offer warranty and post-warranty service, which is crucial for the long-term reliability of the system. Thanks to its own service team, Watrex Praha provides all needs from maintenance and service to the availability of all necessary spare parts and filters for its own water systems or HealForce brand water systems.

Conclusion 

The selection of a laboratory water purification system should be carefully considered based on the specific requirements of the workplace. Key factors include the required water purity, feed water parameters, purification technologies, capacity, operating costs, and service availability. Investing in the right system ensures optimal conditions for laboratory experiments and the protection of sensitive analytical methods. At Watrex Praha, we are fully available to assist you in selecting the best solution for your needs! Contact us at [email protected] or visit our website at www.watrex.com.