As instruments have become more sensitive and applications increasingly complex, the demand for high-purity water has also increased. Parts-per-million (ppm) is no longer the smallest level of contamination, as users are testing for parts-per-billion (ppb) or parts-per-trillion (ppt) levels. Contaminants in water can consist of particulates, organics, inorganics, microorganisms and pyrogens. Renaud Bardon, director for North American Sales, Lab Water at Millipore, says in the past, people were mainly concerned with ionic contaminants, but today, people are more concerned with organic contaminants, particulates and microorganisms.

Eight commonly used methods to purify water are distillation, deionization, reverse osmosis, activated carbon filtration, microporous filtration, ultrafiltration, ultraviolet oxidation and electrodialysis. The National Committee for Clinical Laboratory Standards (NCCLS) has specified three types of water: I, II and III, as well as special-purpose water, depending on their use. Type I refers to the purest water on the scale and is used for most analytical applications, while Type III water is used for general washing. Special-purpose water refers to water that has been treated to remove specific contaminants.

When selecting a water purification system, several factors need to be considered. However, according to Bob Applequist, product manager at Labconco, the most important ones are to fit the product to the application and differentiate between the need for pure and ultrapure water. In most cases, the pure water generated from tap water can be used for most applications, while ultrapure water generated from a point-of-use system can be used for applications that have more specific and stringent purification needs. The first-step purification or the system that is used to convert tap water into pure water has to be very efficient, says Bardon. If you have that first step right, converting that pure water into ultrapure water is going to be very easy and consistent.

When considering a water purification system, both the quality and the quantity of water have to be taken into account, as well as daily water volume requirements, says Bardon. For labs with variable demands on quality and quantity, flexibility and modularity become very important. The key then is to invest in a flexible system that will meet your needs today and grow with the lab and change with the applications, says Matthew Hammond, global sales and marketing director for ELGA LabWater.

After choosing the right system, performing regular, preventative maintenance is equally important. Modern systems have built-in alarms and calibrators that warn customers if certain components are nearing the end of their life cycles. Sample the water routinely to make sure that it doesn’t contain impurities that will interfere with your analysis, says Hammond. The level of monitoring can be done daily, weekly or monthly, depending on the stringency of the application. Whatever system you buy, make sure its dynamic, so that the water can recirculate regularly, Hammond adds. Water needs to be kept moving, as still water ends up building biofilms quicker, so look for a system that is easy to sanitize.


• Produces high-quality ultrapure water (Type I) and pure water (Type II)
• CRYSTA 1000 and 2000 models require reverse osmosis or deionized water as input source and can be used with CRYSTA 500 to create a complete purification system
• Features a timed dispense mode for walk-away, unattended operation

Aurora Biomed


• Produces analytical grade water on demand
• Features easy push-button operation and quick sanitization regimens
• Recirculation feature maintains optimal water quality while minimizing bacterial growth
• Produces up to 18 megohm ASTM water quality

Siemens Water Technologies


• Delivers up to 2 liters per minute of type I, II and III water
• Flexible dispense tip filtration guarantees microbial purity <1CFU/10ml
• Water purity maintained by recirculation of purified water through ion exchange and UV purification technologies to the dispense point

ELGA LabWater

Q-POD® Element Unit

• Ensures delivery of ultrapure water with very low levels of elemental contamination
• Features a footswitch for hands-free water delivery
• Ideal for use in a Class 1000 clean room environment
• Supplies water in volumes required by the user (up to 1.5 L/min)