Reverse osmosis machines are an increasingly common fixture in decontamination rooms. They offer a readily available source of deionized water for application in steam sterilisers.
We often get asked whether or not to use RO water in dental unit waterlines, the answer depends on the quality of the water being produced by the RO machine. Often the water being produced by RO machines is over 100 C.F.U, the EU drinking water standard, and thus not suitable for use in dental unit waterlines.
Reverse Osmosis occurs when pressure is applied to a solute solution causing it to pass through a membrane to a lower concentrate solution. The idea gained ground in the 1960s as a way of making drinking water from saltwater. Today it is used in desalination plants across the world.
It can also be used to remove impurities both natural – such as excess fluoridation – and man-made – it’s not known as from ‘toilet to tap’ for nothing – from water supplies.
These days its use is widespread in everything from winemaking to the creation of maple syrup.
Such systems typically include a sediment filter to trap particles; an activated carbon filter to trap organic chemicals, and chlorine; a reverse osmosis filter which is a thin film composite membrane and, sometimes, an ultra-violet treatment to disinfect any microbes that may escape RO filtering.
In the dental environment, the RO system is usually found as a component of an autoclave used for sterilising small and specialist tools.
RO membranes eventually become blocked over time, if the pre-RO filters are well maintained they can last for many years but, crucially, a mere visual inspection won’t confirm when it needs replacing. Water has to be tested regularly to make sure it is up to scratch. Failure of these membranes can result in the RO machines producing water that is well outside the drinking water standard of under 100 C.F.U. If this water is then introduced into a dental unit waterline, biofilm growth is encouraged and the dental chair is producing water that is over the EU standard.
Some practices may take a TDS (total dissolved solids) reading with either a D-D handheld or inline TDS meter and assume their water is clean. But the TDS result doesn’t measure the microbiological load so the water may look crystal clear but there could still be a hidden danger.
We tend to recommend that tap or distilled water is used in dental unit waterlines, simply because we have seen so many cases of RO machines producing less than acceptable water quality. That being said we always recommend you test your water source, whether that is tap or RO, to ensure it is of drinking quality.
Use one of our HPC Samplers to assess whether or not your water source is producing drinking quality water. If the Sampler test is a pass then you can use the water source in your dental units. If it fails then you should look to use an alternative water source. In addition, a fail test from an RO machine indicates the membranes need replacing, contact your machine provider for more information.
At Aura Infection Control, we are testing a point of use filter that treats water produced by reverse osmosis machines that are struggling to create drinking water consistently. Keep an eye on our website and social media platforms for more information on these filters.
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