Wet and Dry Vacuum – Getting The Most From It.

WVD570 The wet and dry vacuum cleaner can be a very powerful tool, it offers flexibility and value for money by providing a two in one package. This is, however, a double-edged sword, as on one hand, you have one machine that can do two jobs saving space and money, on the other hand, you are dependent on one machine, and need to care for it as such.

However, to get the most out of the machine it is important that it is used correctly, ensuring it is used in the right way will not only increase the lifespan of the machine but ensure that the cleaning performance you had when you first unpacked it is still there in 5 years time.


The first thing you can do to ensure your wet dry vacuum stays in good health (and this goes for wet-only machines too) is to ensure that it is always used with LOW FOAMING cleaning solutions.

Float FilterWhy is this important? Although Numatic wet vacuums have a wet float filter and net that protects the motors from water droplets, the foam is not as dense as water and not dry either. The float on wet vacuums relies on water to lift a ball or float into place to block the flow of fluids into the motors (this goes for other brands too), foam just is not dense enough to lift the float and therefore the foam can get past the float and into the motors causing damage over time.

TIP:  If you are picking up unknown solutions that you think may contain a foaming chemical, then there is a simple trick that is cheap and easy that can prevent foaming within the drum. Drop a bar of soap in the bottom of the drum, job done. This breaks up any water surface tension and also pops bubbles, ensuring that no foam can reach the motors.  It is still worth keeping a close eye on what is going on though, any liquid appearing from the rear vents of the machine indicates that foam has made it into the motors.

Tritex FilterFitting The Correct Filtration

When people purchase a wet or dry vacuum cleaner it is often assumed that it will be fine to deal with whatever you happen to be sucking up, regardless of what filter is fitted, and that the only benefit of running it with the right filter is some added performance. However, using the incorrect filter for a task has similar consequences to having foam build up.

We will cover using the wet filter fist as this is what most people buy a wet-dry vacuum cleaner for.

When using the machine with the wet float fitted it is important that it is only used for wet applications, the reason being that the float system is only designed to prevent water from passing through. If you collect a large deposit of sand it will not only form a type of mud in the drum which can be a pain to clean out, but it will get through the float and then head straight for the motors. Like any machinery, a vacuum motor does not like to have an abrasive substance ran through it.

The best way to deal with dry deposits if you have the vacuum in “wet mode” is to add water, just mop the dry deposit or hose it down and make it into a solution, the vacuum will then be able to deal with the solution without any problems.

At the other end of the spectrum is using the vacuum cleaner for wet use with the dry filter fitted, this is the more dangerous of the two for the vacuum cleaners health. The dry filters are excellent at keeping dust and debris trapped in the drum where you want them to be, but not so good at preventing water from passing through.

As with the foaming issue mentioned earlier in the article, when used for wet use with the dry filter fitted the vacuum is open to water entering the motors. This can happen one of two ways, either the vacuum is filled with water until reaches the motors (after all there is no float to stop it) or the water droplets that enter the vacuum saturate the dry filter then make their way through to the motors again.


By ensuring the vacuum is run with the right filters you are guaranteeing its reliability and future performance. We should also mention at this point that by using the right filters you are ensuring that you stay within the terms of Numatics warranty (see here: )

A lot of what has been mentioned here also applies to other brands of vacuum cleaners, as they all operate a very similar system.

If you have any questions or comments about anything mentioned here then please feel free to contact our support team on our Freephone number to ask, alternatively you can contact us through our Google+ page.



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