Laboratories and life-sciences facilities need water treatment because tap water carries dissolved minerals, organic compounds, particles and bacteria that can interfere with analyses, contaminate cultures and damage equipment. Purified water is produced in stages, usually pre-filtration, reverse osmosis and deionisation, with fine membrane filtration or UV where the application calls for it.

Why tap water is not good enough for lab work

Mains water is safe to drink, but it is far from pure. It carries dissolved ions such as calcium, magnesium, sodium and chloride, traces of organic compounds, fine particles, and the chlorine added to disinfect it. In the lab, those impurities can skew results, react with reagents, leave residues on glassware and scale up glassware washers and autoclaves.

Laboratory water is graded by purity. The international standard ISO 3696, Water for analytical laboratory use, specifies three grades for inorganic chemical analysis, from grade 3 for general wet chemistry to grade 1 for the most demanding work. Your methods and instruments will tell you which grade you need.

How purified water is produced

1. Pre-filtration

Sediment filters remove particles, and activated carbon filters remove chlorine. This protects everything downstream, because chlorine damages most reverse osmosis membranes.

2. Reverse osmosis

Reverse osmosis forces water through a semi-permeable membrane that holds back most dissolved salts, organics and particles. It does the bulk of the purification at a low running cost. Browse our reverse osmosis range and commercial RO systems.

3. Deionisation

Deionisation uses mixed-bed ion exchange resin to swap the remaining ions for hydrogen and hydroxide, which combine to form water. Placed after reverse osmosis, it polishes the water to a much lower conductivity, and the resin lasts far longer than it would on untreated tap water. Options include the Spectrum PRDI nuclear grade deionising cartridge, refillable MB400 deionising cartridges and MB500 colour-change resin, which changes colour as it becomes exhausted.

4. Fine filtration and disinfection

Purified water has no chlorine left to protect it, so bacteria can grow in storage and pipework. Absolute-rated 0.2µm membrane filters, such as the Spectrum PES range, remove bacteria and fine particles at the point of use, and UV disinfection helps control bacteria in the system.

Which treatment does which job?

Application Typical need What helps
Glassware washing and rinsing Spot-free rinse, no scale in the washer Reverse osmosis
General wet chemistry and reagent make-up Low dissolved solids Reverse osmosis followed by deionisation
Autoclaves and sterilisers Purified feed water to the manufacturer's specification Reverse osmosis, with deionisation if a lower conductivity is specified
Cell culture and microbiology Low bacteria and particles Purified water through a 0.2µm PES membrane filter
Small or occasional demand Purified water without a full system Refillable deionising cartridges with replacement resin

How to choose the right setup

  1. Identify the grade you need. Check your methods, instruments and equipment manuals for the water quality they specify.

  2. Estimate your daily volume. Small volumes may suit deionising cartridges alone, while larger demand is cheaper to run on reverse osmosis with deionising polish.

  3. Know your feed water. Hardness and dissolved solids affect how long resin lasts. A water test kit is a good starting point.

  4. Plan monitoring and maintenance. Measure conductivity at the outlet, and schedule cartridge, resin and filter changes.

  5. Ask us if you are unsure. Send us your application, required grade and daily volume, and we will recommend a setup to match.

Medical and dental sites should also see our guide to water treatment for care homes, dental and medical practices.

Why buy from Wrekin Water

Wrekin Water is a family run company based in Bettisfield, Shropshire. We have served more than 50,000 customers over 15 years and are rated Excellent on Trustpilot. We stock Spectrum filtration alongside Pentair Fleck, Autotrol, Clack, Kinetico and other major brands, so replacement cartridges, resin and membranes are easy to source. Find out more about why customers buy from us.

Get the right water for your lab

Tell us what your lab does, the water grade you need and roughly how much you use, and we will recommend a setup that fits. Contact the Wrekin Water team or shop reverse osmosis.

Frequently asked questions

Reverse osmosis pushes water through a membrane that holds back most dissolved salts, organics and particles. Deionisation uses ion exchange resin to remove the remaining dissolved ions. Labs often use both together: reverse osmosis does the bulk of the purification cheaply, and deionisation polishes the water to a lower conductivity.

It depends on the work. ISO 3696 sets out three grades of water for analytical laboratory use, from grade 3 for general wet chemistry to grade 1 for the most demanding analyses. Your methods, instruments and equipment manuals will specify the quality they need.

Measure the conductivity of the water leaving the cartridge, which rises as the resin becomes exhausted. Colour-change resin such as MB500 also gives a visual check, because it changes colour as it is used up.

Yes, and for small volumes that can be the simplest option. On hard or high-mineral tap water, though, the resin is used up much faster. Putting reverse osmosis in front removes most of the dissolved minerals first, so the resin lasts far longer.

For bacteria-sensitive work, usually yes. Purified water has no chlorine left to protect it, so bacteria can grow in storage and pipework. An absolute-rated 0.2µm membrane filter at the point of use removes bacteria and fine particles, and UV disinfection helps control growth in the system.