Understanding water quality recommendations as per ISO 11133: 2014 standard


Jean Christophe Hemy, Global Product Manager, Milli-Q Lab Water Solutions is a specialist in lab water purification technologies and has long expertise in bioburden, sterility testing, and sterile filtration at Millipore and Merck, and has also extended support to microbiology quality control laboratories. Microbiology testing is of major importance to guarantee the safety and quality of food. Laboratories performing these tests are required to deliver accurate and reliable results and meet regulatory requirements while under time pressure. Many tests and procedures depend upon culture media being capable of providing consistent and reproducible results. Hemy talks about the role of water in microbiology applications, water quality requirements recommended in EN ISO 111:33 and how to obtain it

What are the water quality requirements recommended in EN ISO 11133: 2014 standard for the quality of the culture media used?

 For culture media preparation, EN ISO 11133 recommends using only purified water free from substances likely to inhibit or influence the growth of the microorganisms under the test conditions for example traces of chlorine, traces of ammonia and traces of metal ions. The purified water shall be stored in tightly closed containers made from an inert material however recommended that the water is used as soon as produced. Microbial contamination should not exceed 103 cfu/mL and preferably be below 102 cfu/mL. The conductivity shall be no more than 25 μS/cm (equivalent to resistivity ≥ 0.04 MΩ cm), preferably below 5 μS/ cm (grade 3 water, ISO 3696) at 25 °C. The conductivity should be checked before use. 


What role does the quality of lab water play in the microbiology laboratory and other sensitive analysis like HPLC / LC-MS / ICP-MS?

 When preparing culture media, it is important to select the correct water quality, since water may contain impurities that can affect media productivity or cause abnormalities such as incorrect pH, wrong colour or precipitation, as indicated in Annex H of the EN ISO 11133 standard. Due to the use of contaminated water in the testing, the user may find difficulties in interpreting the data. It may give erroneous results, which may cause you to repeat your analysis and source the sample/reagent again. Increasing TOC level results in extraneous peaks on HPLC baselines, formation of Na+ adduct peaks and additional peaks in LC-MS Mass Spectra. Contamination may also cause fluctuation in detection limit due to high BEC and may cause calibration curve failure.


Food quality regulations are becoming stringent across the globe? How does Milli-Q® Lab Water Solutions comply with these standards at the global and Indian levels?


Merk is supporting F&B Industry across the world. In India also, we have partnered with the leaders in the F&B segment taking care of their water-related concerns, so that they can focus on their vital work. To comply with the stringent regulations, we performed a study in the Merck KGaA Life Science QC laboratory for microbiological products in Darmstadt, Germany. The laboratory is accredited by the German accreditation authority DAkkS as registered test laboratory D-PL-15185-01-00 according to DIN EN ISO/IEC 170252 for the performance testing of media for microbiology according to DIN EN ISO 11133. Water purified by the Milli-Q® IX water purification system fitted with a 0.22 μm final filter was confirmed as validated to deliver water meeting or exceeding the water quality requirements of the EN ISO 11133 standard.



Distillation is one of the oldest and popular techniques of water purification used in many laboratories. How is a water purification system better than a distillation technique?


Yes, distillation is the oldest method but it’s slow, requires a lot of energy and water, and needs regular cleaning. Sterile water produced remains subject to contamination along with storage. The water purification system combines several purification technologies recommended in the ISO 11133 norm to effectively remove all contaminant types and ensure reproducibilities such as Depth Filter, Activated Carbon, Reverse Osmosis, Electro-Deionization, UV lamp, and 0.22µm final filter. Along with those steps, resistivity cells allow to real-time monitor the purification process and water quality improvement.


How has the water purification technology advanced over the years and what role does Milli-Q® Lab Water Solutions play as a pioneer?

 From developing the ElectroDeionisation Elix® modules 40 years ago that ensures constant water quality production without ion resins regeneration drawbacks, to today offering compact systems, versatile installations, flexible and multiple dispensing modes, and easy remote access to the system and dispensing events data, we are continuously innovating keeping our customers current and future needs in mind.


Merck is a Platinum Ecovadis Member. What steps company is taking for providing sustainable solutions, which is a growing requirement of the industry?

 This recognition placing us in the top 1 per cent of all companies assessed and it comes from years of engagement in that direction. Elix EDI eliminates the need for hazardous chemical regeneration and associated waste. E.R.A. technology optimises water recovery from RO membrane, reducing water use by up to 50 per cent. The Milli-Q® IX pure water systems achieve up to 30 per cent energy savings (>500 kWh over the product lifecycle) vs. previous generation Elix® systems. ech2o® UV lamps are Mercury-free, compliant with the latest regulations. Our sites are ISO 14001 certified and our systems comply with critical environmental regulations, such as RoHS, REACH and WEEE. In addition, as a member of the Together for Sustainability (TfS) network, we strive to work with suppliers that have been audited for sustainable supply chain practices.


How do you help your customers achieve optimum water quality for F&B testing applications?

 Microbiology media preparation is supported by the Milli-Q® IX water purification system which provides consistently high-quality pure water thanks to its combination of innovative purification technologies like reverse osmosis, Elix® EDI, bactericidal UVC LED, and 0.22 µm filtration. Stored water is protected against airborne contaminants by a vent filter. An ergonomic E-POD® water dispenser provides easy delivery of pure water. It has an HD touchscreen giving real-time access to system data and water quality. In addition, water from this system can feed lab equipment, such as autoclaves or dishwashers, making it a versatile solution for microbiology laboratories. 


Water purified by the Milli-Q® IX water purification system fitted with a 0.22 μm final filter is validated to deliver water meeting or exceeding the water quality requirements of the EN ISO 11133 standard. It is validated to deliver water with conductivity < 0.2 μS/cm; typically 0.1 μS/cm. Data obtained during the system’s validation process: Free chlorine < 0.02 ppm, Ammonia ≤ 0.00003 per cent, Heavy metals ≤ 0.00001 per cent, and microbial contamination ≤ 102 cfu/mL.

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