Can You Use a Pressure Washer with Low Water Pressure?


One of the most important things while using a pressure washer is to have a sufficient water supply. The pressure or capacity of this supply must match with the GPM (Gallons Per Minute) rating of your pressure washer. If the amount of water is lower or the pressure is not sufficient, the pressure washer may not work correctly.

Can You Use a Pressure Washer with Low Water Pressure?

It is no problem to use a pressure washer with low water pressure. Each pressure washer model has a certain minimum pressure it needs to operate. Most models recommend a minimum pressure of around 20 PSI. But my experience is that it still works fine even if it is slightly lower than that. Some models can work with water from a bucket, so with no water pressure. In that case, the pressure washer will pump the water.

Can You Use a Pressure Washer with Low Water Pressure? 1

This article will provide you with all the information on using your pressure washer with lower water pressure. I will also look at things you can do to increase the pressure of your water system.

How can you see if the water pressure for your pressure washer is low: Cavitation

The most common problem that occurs due to low water pressure is cavitation. Air cavities form inside the water supply that causes a loss in capacity and pressure of the water supply and a significant drop in efficiency as well. The pressure washer becomes noisier and vibrates a lot more when the water inside the water supply becomes saturated with those air bubbles. The reason for this is that the cavities leave the low-pressure area and pass into the high-pressure area. Cavitation can even cause small explosions that can blow up your pressure washer pump.

Cavities are formed due to different reasons. The most common reason for cavity formation is vaporization, which occurs due to the high temperature of the water. Freshwater must be used with a pressure washer as the pumps are designed to be operated with freshwater. Another cause of cavitation is air ingestion, which can also cause damage to the pump of the washer. But the consequences are less severe than with vaporization. It also causes a loss in the capacity of the pressurized water.

Is It Safe to Use a Pressure Washer With Low Water Pressure?

A pressure washer can safely be used at locations that have low water pressure. Only ensure that the water pressure is near the minimum value your pressure washer needs. A lot of pressure washers need a minimum pressure of around 20 PSI. Even do my experience is that with a somewhat lower PSI they still work fine. Use a pressure gauge to measure that pressure at the hose.

Except for the minimum pressure, the amount of water also needs to be such that it supplies enough for the pressure washer to run. You can check the amount of water your water supply provides to the pressure washer by placing a one-gallon bucket under the spigot and measuring how long it takes to fill the bucket. For example, if the bucket gets full in 30 seconds, then the GPM rating of water supply is 2 (1 divided by 0.5 minutes), which is fine for most pressure washers.

If the GPM rating of the pressure washer is 3 GPM, I do not recommend using it with a 2 GPM water supply. Generally, most pressure washers used for household cleaning have a GPM rating of around 2. Industrial units often require a 3 GPM rating or more. These machines should not be used with a water supply of 2 or 2.5 GPM. You increase the GPM of your water supply by using a hose with a larger diameter. Of course, this will only work if the faucet can supply a higher GPM level.

How to Check Your Water Supply’s Pressure?

The easiest way to determine the pressure of your water supply is to use a pressure gauge. You can connect it to the faucet or install it near the main valve, where the water pipe enters your house. To measure the Gallons per Minute (GTM), you can use a 2 or 5-gallon bucket and a stopwatch. Place the bucket under the tap and open it. Use the stopwatch to measure how long it takes to fill the bucket. Now you can easily calculate the GTM.

When the pressure washer’s pump doesn’t receive sufficient pressure, it can run hot. And can damage its seals, gaskets, and other components. Water is needed for cooling. Ensuring that your water supply has sufficient water pressure to operate the pressure washer is very important.

An easy way to determine the pressure of the water supply is to use a 2 or 5-gallon bucket. You must decide the type of pressure washer you are going to buy beforehand. For an electric pressure washer, place the 2-gallon bucket under the running tap. If the bucket gets full in a minute or less than 60 seconds, the pressure of your water supply is adequate to operate an electric pressure washer.

Similarly, if you decide to buy a gas pressure washer, you can use a 5-gallon bucket and see if it gets ¾ full in a minute. You can also use a 1-gallon bucket if you don’t have a 2 or 5-gallon one. Divide 60 by the number of seconds in which it gets full. For example, if a 1-gallon bucket gets full in 15 seconds, the GPM of your water supply is 60/15, equal to 4 GPM. You can also install a pressure gauge to check the pressure of your water supply.

What Do I Do If My Pressure Washer Has a Low Water Supply Pressure?

Low water supply pressure can affect the correct working of your pressure washer. If the amount of water (Gallons Per Minute, GTM) is ok, but the pressure is low, there are several ways to increase it. If the water pressure from the pipe that enters your house is ok, you can increase the pressure by changing the setting on your water pressure regulator. Or replace the pressure regulator if it does not function correctly. If the pressure entering your house is already low, you can install a water pump.

Insufficient water pressure on your outdoor faucet can be due to the low pressure of the water supply. The pressure of the water supply can be measured with a pressure gauge. You can place the gauge near the main valve where water enters your house. Or you can connect it to the faucet. If the gauge shows a reading of less than 20 PSI, then your water supply pressure is insufficient. There are three main ways to increase the water supply pressure.

● Improve the pipes between the main stopcock and the faucet:

If you measure the pressure near the stopcock, and it is fine. But the pressure near the faucet is much lower. It means that a lot of pressure is lost on the way in the pipes. It can be that the pipes are clogged somewhere. The length can be an issue, or there are a lot of bents. When water flows through the pipes, it will have resistance. Resistance will lower the pressure. The longer the pipes, the lower the pressure will be at the end. The more bends it has, the lower the pressure will be. And if the pipes are partly clogged somewhere, this will lower the pressure as well. Always try to have a connection that is as short as possible, with the least amount of bends. And if you suspect a partly clog somewhere, you have to clean it. Flush your water lines and descale your pipes and faucets.

Steps to Descale Your Pipes and faucet:

  • Step 1: Fill several buckets with hot water. There should be enough to fill all the pipes you are cleaning.
  • Step 2: Turn off the main stopcock.
  • Step 3: Empty the pipes by opening the faucets and the drain caps. Let the water out. Flush the toilets.
  • Step 4: Close the faucets and the drain caps.
  • Step 5: Pour the drain cleaner into the pipes. If you open the drain cap, you can do this from the side of the faucet. You can use a hose for this. When it reaches the drain cap, close the drain cap. Let the liquid stay in the pipes for about half an hour so that it can do its work. Some cleaners need longer, so check the manual.
  • Step 6: Pour hot water into the pipes using a similar way.
  • Step 7: Open the stopcock.
  • Step 8: Open the faucets at full power to clear the pipes and faucets from the deposits.

● Inspect the Water Pressure Regulator:

Low water pressure outdoors can be due to poor adjustment of the water pressure regulator, also known as the pressure-reducing valve. The water pressure regulator is often located along with your main stopcock. When the regulator doesn’t work correctly, the pressure of the water will be lower. First, to inspect the regulator, measure the pressure with a pressure gauge at the point nearest to the water regulator and see if it can be adjusted to increase the pressure. Generally, a PSI rating between 40 to 60 is considered good water pressure. Anything below 20 PSI means that the pressure of your water supply is low.

● Install a Water Pump / Booster Pump

An excellent way to increase the water pressure is to install a booster pump to your main water supply system. There are many types of pumps available in the market, which are used for different purposes. For increasing the water pressure for a single faucet, a regular pump will do the job. This water pump can be installed on the main water supply.

The pump increases the pressure significantly and allows you to achieve a perfect pressure to connect your pressure washer. A water pump often comes with a water pressure regulator that allows you to set the pressure according to your choice.

Can I Use a Pressure Washer With a Well?

In general, you can safely use a pressure washer with a well. Always check that the water flow from the well pump matches the GPM rating of your pressure washer. And that the water pressure is equal to or higher than the minimum pressure washer water supply pressure. Generally, residential wells do provide more than enough pressure and GPM for pressure washers to operate.

Residential wells can provide 100 to 120 gallons of water per day. This means an average flow rate of 4 gallons per minute for 4 hours. Most pressure washers used for regular household cleaning require 2 GPM. So, you can safely use a pressure washer with a well without worrying about causing damage to your pressure washer.

If you feel that your well pump cannot provide an adequate amount of water for your pressure washer, I recommend to use another type of water supply. Not providing enough water or pressure to the pressure washer can damage the pump.

Can I Use a Booster Pump If the Pressure Is Low?

A booster pump is one of the best options to increase the water pressure. You can use it to increase the water pressure for your whole house. Or just for a particular faucet with a small pump.

A booster pump is a machine that helps to increase the water pressure and flow. They cost in the $350 to $1000 range and can increase the pressure to above 60 PSI and handle flows up to 18 GTM or more.

If you have a gravity water tank, it can bring the water pressure to the desired level, even on the top floors. The water pressure it can deliver will be fine for all pressure washers.

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