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Does a Pressure Washer Need Water Pressure? Are There Pressure Washers for Low Water Pressure?

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One of the most important factors with using a pressure washer is having a sufficient water supply, along with suitable pressure. The capacity or pressure of the water must match the GPM (gallons per minute) rating of your pressure washer, and if the water pressure leaving the gun is not sufficient enough, the pressure washer is likely to not work correctly.

This article will provide you with all the relevant information on the required water pressure for optimum pressure washer use, and measures to take if you have a low-pressure water supply!

How Much Water Pressure Does a Pressure Washer Need?

First things first, to determine what a low-pressure water supply is, let’s bring to your attention the amount of water pressure that a pressure washer needs. An average household spigot will supply about 30-40 PSI when turned on the whole way. Most modern-day pressure washer manufacturers recommend that you have a consistent supply of 20 PSI water to your device.

So, if you’re using the outdoor spigot on your house, you really don’t have much to worry about at all! As long as you have the water supply open over halfway you should have adequate pressure for the task.

One factor you should consider, however, is the length of your garden hose supplying the pressure washer. With increased lengths in the garden hose come increased drops in pressure. Therefore, a 25-foot garden hose will have more PSI at the end of it than a 50-foot garden hose. You don’t want to use too long of a hose, and effectively lose the PSI that is required for you to operate the pressure washer optimally.

How to Detect Low Water Pressure for Your Pressure Washer

The most popular problem that occurs when a pressure washer has too low of water pressure is cavitation. This is where air cavities form inside a water supply and cause a loss in capacity, pressure, and a significant drop in the overall efficiency.

When cavitation occurs, and something you should look out for, the pressure washer becomes significantly noisier and will then vibrate a lot more when the water becomes saturated with air bubbles. Cavitation can cause small explosions that can blow up your pressure washer pump, so they really are something you should aim to avoid.

Low pressures may not be the only cause of cavity formation inside your pressure washer. One of the most common reasons for cavity formation is vaporization, which occurs due to the high temperature of the water in the pump. Another cause is air ingestion, which will lead to damage to the pump of the pressure washer too.

How to Check Your Water Supply’s Pressure

The easiest and quickest way to determine the pressure of your water supply is to use a pressure gauge and attach it to the faucet or install it near the main valve where the pipe enters your house.

Otherwise, you can use a bucket and a watch to measure the gallons per minute (GTM). It’s typically recommended to use a 2 or 5-gallon bucket and place it under the tap before opening the tap. You can then use the watch to measure the length of time it takes to fill the bucket.

For an electric pressure washer, place the 2-gallon bucket under the running tap. If the buckets fill in less than 60 seconds then the water supply is of adequate pressure to operate your pressure washer.

For a gas pressure washer, place a 5-gallon bucket under the tap and see if it gets 3/4 full in around 60 seconds. If you only have a 1-gallon bucket at hand, no problem! Use the same process with the 1-gallon bucket and this time divide 60 by the number of seconds in which it takes to get full.

For example, if your 1-gallon bucket takes 30 seconds to fill, the GPM of your water supply is 60/30 which is equal to 2 GPM.

Using a Pressure Washer With Low Water Pressure

Pressure washers can safely be used in various locations that have low water pressure. I would just advise using a water pressure that is similar or as close to the pressure washer’s requirements as possible.

Most pressure washers need a minimum of 20 PSI, but many users have sworn by their effective operation at lower pressures than this. In general, I will advise that if your pressure washer has a 3 GPM rating, you should not use it with a 2 GPM water supply.

Typically, you will find household cleaning pressure washers with 2 GPM ratings and then industrial units that have a 3 GPM rating or greater. The industrial pressure washers will need a water supply similar to their rating to operate efficiently, you won’t get away with your home supply!

Ways to Increase Low Water Pressure for Pressure Washer

Low water pressure can affect the efficiency of your pressure washer. It’s possible that the GTM of the water supply is adequate, but the pressure is too low, and so, you may wish to look for ways to increase the water pressure.

Insufficient water pressure on your outdoor faucet can be due to the flow pressure of the water supply, which can be measured with a pressure gauge. By placing the gauge near the main valve where water enters your house or connecting it to the faucet, you will be able to read the gauge and see if there is a reading of less than 20 PSI. If your pressure gauge reads below 20 PSI, you have an insufficient pressure supply.

To increase the pressure of the supply of water for your pressure washer, there are 3 main methods:

  • Improve the piping system
  • Inspect the water pressure regulator
  • Install a water pump

Let’s look at each in more detail!

Improve the Piping System

If you are able to improve the pipes between the main stopcock and the faucet, you may be able to increase the available pressure of water. If measuring the pressure near the stopcock and it appears to be fine, but the pressure near the faucet is much lower, this is a clear indication that something in this system is causing a pressure drop.

It could be that the pipes are clogged somewhere, or the length of the pipes or the number of bends in the system is the issue. The more resistance in a piping system, the more the pressure will be lowered. The longer the system and the more bends it has will directly lower the pressure at the end.

You should always aim to have connections that are as short as possible, with the least number of bends. If you suspect that your pipes may be clogged somewhere, you should inspect and clean them. It’s very important to flush your water lines and descale your pipes and faucets. Here is a step-by-step guide on how to descale your pipes and faucet.

  1. First, fill several buckets with hot water, or enough to fill all the pipes you are cleaning.
  2. Turn off the main stopcock and open the faucets and drain caps to empty the pipes.
  3. Close the faucets and drain caps before pouring the drain cleaning into the pipes. If you open the drain cap, you can do this from the side of the faucet using a hose. When it reaches the drain cap, close the drain cap and let the liquid stay in the pipes for 30-60 minutes.
  4. Pour hot water into the pipes using a similar method
  5. Open the stopcock and the faucets at full power to clear the pipes and faucets from the deposits.

Inspect the Water Pressure Regulator

Low water pressure outdoors also be due to poor adjustment of the water pressure regulator, sometimes referred to as the pressure-reducing valve. The water pressure regulator is often located along with the main stopcock.

If the regulator is not working properly, the water pressure will be lower than expected. To inspect the water pressure regulator, measure the pressure with a pressure gauge at the nearest point to the water regulator to see if it can be adjusted to increase the pressure.

In general, a 40 to 60 PSI rating is considered good water pressure. Anything below 20 PSI means that the pressure of the water supply is low and potentially problematic.

Install a Water Pump

A final and excellent method for increasing the water supply pressure is by installing a water pump or booster to your water mains system. Pumps are available in a wide array of types for numerous applications, but a regular pump installed on the main water supply should be ideal for increasing the water pressure of a single faucet.

The pump increases the pressure of the water significantly and will allow you to achieve a perfect pressure to supply your pressure washer. Most water pumps will come with a water pressure regulator that will allow you to set the pressure according to your requirements.

Alternatively, this YouTube video below is a useful demonstration on how to solve the pressure washer low pressure problems.

FAQs (Frequently Asked Questions)

Does a pressure washer need water pressure to start?

It is possible to start a pressure washer with low water pressure as the pressure washer will create its own pressure. Pressure washers do typically need water that is rated at a minimum of 20 PSI but they should be able to work with lower pressures. All you need is enough water pressure to get the water to the pressure washer, and then the pressure washer pump will take over from there.

Can you run a pressure washer from a bucket?

You will be able to run a pressure washer from a bucket if you have a suction hose to draw the water from the bucket and into the pressure washer. The only issue you may have here is the limited water supply, causing you to cease operation quite regularly so that you can refill the bucket.

Do pressure washers need to be connected to a tap?

Pressure washers don’t necessarily need to be connected to a tap, any water supply will suffice! The water supply can be from a tap, a bucket or water barely, or even a nearby river or lake if a suction hose is used.

How much water pressure does it take to run a pressure washer?

Most pressure washer manufacturers state that their products need a minimum rating of 20 PSI water supply to be able to operate efficiently. A lot of pressure washer users swear by being able to sufficiently operate some pressure washers on less pressure, and some industrial pressure washers may require greater pressures. Therefore, the amount of water pressure required to run a pressure washer really depends on the exact pressure washer you have as it will vary from model to model.


If you have any questions about pressure washers needing water pressure, please leave a comment below, so that someone can help you!

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