Could I use a pressure washer on a house with a well pump? Should I be concerned about the pump running for a long period of time i.e. 4 hours? half a day while we wash the outside of the house?
Most consumer-grade pressure washers require the input water to be at least in the low range of typical household pressure from a municipal water supply. It also needs to be continuous; if a well can't keep up with the demand, you'll destroy the pressure washer.
But, there's an option: operate from a tank of water with a pressure washer that can operate with a siphon feed.
Even small gas pressure washers typically use 2.5 - 3.5 gpm, so 4 hours of run time would require on the order of a 600 - 900 gallon or larger tank. But a gas pressure washer can clean a large area quickly, so you may not need 4 hours of run time. Electric washers use half of that.
You prefill the tank at a convenient time. You can also fill it with captured rain water, like from your downspouts, that you filter REALLY well.
While most consumer pressure washers can't operate from a siphon, there are a few that can. For example the high-end Karcher machines can, and they sell a siphon adapter kit for them.
If you can rely on your well for continuous volume at around 2 gpm, you could feed a siphon-capable electric washer without needing a tank or worrying about run time.
You have a simple engineering problem. The house well pump has to be able to put out enough water to handle the house loads, plus the washer. I would look for about a 25 to 30% buffer in capacity over the well pump output capability and the pressure washer needs.
All bets are off if everyone in the house decides to fill a tub at once, while the dishwasher and clothes washer are filling.
Your best bet is to look at name plates and correlate the model of pump, with the depth of your well. It would be good to run your garden hose wide open for 15 to 30 minutes and measure the flow. If you well has a low capacity, it may not be the well pump that it the issue, it may be that the well continually drops in pressure as the level lowers, and the GPM output also keeps dropping.
Let's say you are lucky and you estimate that your well pumps out 15 GPM and your pressure washer needs 5 GPM. Than assuming that your bathtubs don't all fill at once, you may be just fine.
Because well outputs, pumps and pressure washers vary quite a bit you have to do some work getting data by lookup or by experimentation.
Make sure your pressure washer has a good inlet screen. Some wells produce more sand and clay than others. Sand is bad for power washers. So check the screen after 10 minutes and probably quite frequently afterwards to make certain you are getting clean water, without abrasive particulates.
Also keep in mind that as a well gets drawn down, the sand content may go up.
So the issue is to make sure that your supply side can handle your consumption side, and that the quality of the water will not become adverse at your usage level.
To merely run the pressure washer because someone else down the road could, is asking for an expensive repair to the power washer pump.
- Does the well have sufficient capacity?
- Does the well pump have sufficient continuous capacity?
- Is the well water, throughout the usage cycle, of sufficient quality (regarding sand and other particulates)?
- Will the overall system output have sufficient margin, to run the household and the washer for the time desired?