Yes, pressure washers can be run on lower water pressure than most think – only 2 GPM (Gallons Per Minute) is needed to run one, and considering the minimum flow of 6 GPM is standard for a well to supply water to a single-family home, a well should be sufficient.
Pressure washers are immensely useful tools, clearing muck and grime off all kinds of decks, driveways, and tiles. But what do you need to run one? Could you run it off something with low water pressure like a well?
To understand how a pressure washer can be run off a well, we’ll need to discuss how a pressure washer and GPM works, before we can explain anything about wells. Let’s start with the basics of how GPM and waterworks.
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Gallons Per Minute
So, GPM is the main measurement used in these cases – as well as many other occasions within the plumbing. For example, as a consumer, you might have stumbled upon 2 GPM versus 2.5 GPM showerheads in the DIY shops and had no earthly idea what that meant.
Well, in short, GPM is the flow rate of plumbing devices, literally just an acronym of Gallons Per Minute. Your 2 GPM showerhead will pump out 2 gallons of water in a minute whilst the 2.5 one will pump out 0.5 of a gallon in the same amount of time. Refreshingly easy.
However, you have to understand that GPM is based on another measurement you’d need to get to grips with, known as the Head. This isn’t the showerhead when shopping, confusingly enough, but is a measurement of how high water must reach to get pumped through the system.
Head also comes in three different kinds:
- Total Head – which is the highest point the pump can pump water out from, or the discharge point.
- Total Suction Head – which is the height between the source of the water and the pump itself.
- Total Discharge Head – which is the height from the pump to the highest point that it can pump fluid to in the system.
So, in layman’s terms, when looking at water pumps of any kind, be it the showerhead or the pressure washer, we’re looking at how much or how fast it can pump water, and how much pressure it will have when it comes out. To figure this out, we need to figure out how hard the pump will have to push against gravity.
The harder it is able to push against Isaac Newton’s famous force, the higher you can have the discharge point and still have liquid coming out of it.
Naturally, the higher the Head, the smaller the GPM – which makes sense; the higher the end of the shower, the harder the pump will have to pump to get water out of it, so the amount of water coming out will slow down.
I’m sure many of you have experienced this when lifting and lowering your own showerhead. Usually, the measurements of this kind will look like this:
- 140 GPM 40 feet of Head
- 100 GPM 60 feet of Head
- 60 GPM 70 feet of Head
Are you still with me? Good. Now we know the basics of how a pump works and is calculated, it’s time to take a look at pressure washers.
Pressure Washers And GPM
We’ve now discussed GPM and Head and how that affects pumps and the flow of water, we can discuss pressure washers with a bit more understanding. Because pressure washers spit water out at such high amounts, people often think that you need a source with good water pressure to even run the thing – some have even worried that doing so with poor or non-existent water pressure will break it.
Luckily, that’s not true at all. The truth is that a pressure washer creates its own water pressure within the device itself, so all the GPM you really need is just enough for the water to get into the pump, and then the pressure washer can take it from there, which makes sense; if a pressure washer needed the water source to have the power of a pressure washer in order to run, then all outside spigots or hoses would be blasting water out like fire engines.
Why would you need the pressure washer at all in that case? (And could you imagine watering the garden with a hose with that water pressure?)
Now, this isn’t to say that the pressure washer shouldn’t be checked; most pressure washers will say on the box, but some may need a 3 GPM. If you have 2.5 GPM taps, then it might not be good for the pressure washer to plug it in. However, most run at 2 GPM, and most taps run at 2.5 GPM, so there’s not much cause for concern – just something to be aware of.
Wells And GPM
Finally, this leads us back to wells. With their very still waters, people may worry that they won’t be able to run pressure washers, which we’ve already discussed is not the case. On average, a residential well supplies a residential home with between 100 and 120 gallons of water daily, which works out to a flow of between 6 and 12 GPM, which should be plenty.
There is one exception to this that you might need to be aware of, and that is one common circumstance where the well might not have the GPM – if your well’s water feeds into your home without the use of a pump, and the pump only begins to work when the well is running on empty, in that occasion, your well might not be producing the required amount of GPM for a pressure washer.
These circumstances are rarer, however, and most wells should be able to run pressure washers without an issue.
Related Reading: Do I Need to Wear a Mask When Pressure Washing?
Despite worries of people that still water such as wells won’t be able to run pressure washers, the fact is it almost certainly can. This is because the GPM (Gallons Per Minute) required by pressure washers is only around 2 GPM when most wells commonly provide about 6 GPM.
This is because the pressure washers provide most of the pressure within the device itself and only need enough GPM for the water to reach its internal pump. The only exception to this good rule is if the well supplying your home with water does not use a pump to do so, at which point it may not have the GPM required – but this is quite rare.