Frequently asked questions about pressure washers
What is the water flow rate of a pressure washer?
Water consumption is an important factor to consider when choosing a pressure washer. A higher water flow rate allows the pump to deliver more liquid per unit of time, enabling more effective cleaning by removing dirt in a single pass. Generally, the performance of a pressure washer is typically correlated with the power and size.
Compact battery washer has the lowest water consumption. Many of them have a capacity of about 120 — 200 l/h — not much, but quite enough to rinse the bike after a countryside ride or clean window panes in a private house. The simplest household washers, powered by a network, consume up to 350 liters of water per hour of operation. Such performance is still considered low, but quite acceptable for devices that are used in the garage and in the country. A washer can be used for tasks like washing a car or performing regular cleaning around the house.
 |
| To care for the bike, a pressure wash with a small water flow rate is enough. |
High-pressure washers with a water flow rate of 400 to 500 l/h are versatile and commonly available. They are suitable for tasks like car washing and cleaning concrete surfaces with stubborn dirt. However, for more intensive cleaning jobs, it is recommended to invest in a washer with a flow rate exceeding 550 l/h. These models typically feature powerful engines, robust pumps with high pressure, larger dimensions, and a weight of around 20-30 kg. They often come equipped with wheels for transportation and hose reels for convenient storage.
Professional-class devices can also have higher productivity, ranging from 800 to 1000 l/h. However, it is generally unnecessary to purchase equipment with such high water consumption for home use, as they are primarily designed for tackling complex and large-scale cleaning tasks in environments like farms, production workshops, and motor transport enterprises. Many professional high-pressure washers are designed to work on three-phase 400 V power supply or have their own petrol engines, allowing for autonomous operation without relying on electrical sockets.
 |
| And cleaning up after livestock on a farm, for obvious reasons, requires a device with a very high capacity. |
What is the recommended pressure for a pressure washer?
Comparing different devices in the catalog of pressure washers, you can see that they are very different from each other in such a parameter as the maximum water pressure. This characteristic shows the strength of the water jet at the outlet of the nozzle. How to evaluate this parameter, and what pressure should the washer have in order for it to effectively perform its functions? Let's figure it out.
The water pressure in the city's water supply system typically does not exceed 6 bar, while household pumps or ordinary pumping stations in private houses usually reach a maximum of 8-10 bar. These values represent the theoretical maximum pressure achievable using a handheld nozzle gun connected to the water supply or a a spray nozzle on a hose. Compared to high-pressure washers, these pressures may seem relatively low. However, the pump inside a device is capable of generating significantly higher pressures, surpassing those of electric water pumps or a motor pumps by a considerable margin.
 |
| Due to the large pressure of water, the device quickly and effectively washes dirty surfaces. |
Even the least powerful handheld washers, which have the pump integrated into the gun and are battery-powered, typically generate a pressure of at least 20-50 bar. While they may not be suitable for heavy-duty cleaning or tackling stubborn dirt, they are effective in removing dust and light dirt. Such devices find everyday use in tasks like maintaining lawn mowers washing windows, and cleaning the wheels and frames of bicycles, scooters and baby carriages after rides and outings in bad weather.
For car washing and maintaining cleanliness in the countryside a compact pressure washer with a moderate operating pressure of up to 100-125 bar is sufficient. This pressure level, though not very high, is still capable of effectively removing road dust from car bodies, cleaning wooden verandas or ceramic tile floors, and washing garden equipment and plastic garbage containers. Washers with a higher working pressure, around 150 bar, excel at cleaning concrete, brickwork, and masonry. They can handle tough dirt, such as stubborn grime on a concrete driveway or oil stains on a garage floor. Pressure washers with a working pressure of 175 bar or higher are considered heavy-duty equipment and can even strip plaster off walls with a powerful water stream or clean concrete mixers from partially dried cement mortar.
 |
| Washers with a pressure of more than 175 bar are not particularly needed in everyday life, but are indispensable in other areas. |
When selecting a pressure washer, it's important to consider that devices with excessively high working pressures are not suitable for household or car washing purposes. Using a very strong water jet on soft materials and delicate surfaces can cause damage. For instance, a water flow with a pressure of 150 bar can potentially ruin the paintwork of a car, while pressures above 170 bar can result in dents on the body panels or hood. Moreover, a focused stream of water at 200 bar can create a hole through a 50 mm thick wooden board within just 10 — 20 seconds.
Considering the aforementioned factors, it is advisable to invest in a mini pressure washer that offers a wide range of adjustable water pressure. The broader the range, the better. For example, the Karcher K 5 Classic washer allows users to adjust the pressure from a gentle 20 bar, suitable for delicate cleaning, to a more powerful 145 bar, capable of tackling stubborn dirt. The pressure adjustment can be achieved through a regulator on the pump or by switching the motor power mode, depending on the device's design. Some pressure washers provide the option to adjust the output pressure using a nozzle with a swivel tip or buttons on the gun.
 |
| Many Karcher devices have buttons on the gun to adjust the water pressure. |
How much power should a pressure washer have?
When comparing and evaluating pressure washers, the parameters of maximum pressure and water flow are often considered. Power, on the other hand, serves as an indirect indicator that helps determine the equipment's class, performance, and electricity consumption. Household-class washers typically feature electric motors with power ranging from 1500 to 3000 W. More powerful engines are commonly found in «advanced devices, while only a small number of high-pressure washers exceed 4000 watts of power. These higher-powered models are often professional equipment designed for high working pressure and productivity. Some of them even include a water heating function, where a part of the power is allocated to operate the heating element.
How to connect a high pressure washer to the water supply?
To connect a pressure washer to a pressurized water supply, you will need a garden hose and connectors or clamps. The hose should have a sufficient length, typically around 10 or 15 meters, and it is preferable to have reinforcement inside. This is because the hose not only supplies water but also acts as a damper, smoothing out small pressure fluctuations in the system. Manufacturers generally recommend using 1/2" hoses for household washers and larger 3/4" hoses for high-performance devices capable of handling larger water flow rates.
It is recommended to use a check valve between the hose and the faucet to protect the water supply system from water hammer caused by the on/off cycles of the high-pressure pump. Examples of such check valves include Husqvarna 5906595-01 and Nilfisk 106411177. Additionally, some manufacturers suggest using a water pressure reducer to prevent damage to the nozzles inside the pressure washer due to excessive water pressure from the water supply system. Most household pressure washers can tolerate an inlet pressure of up to 10 bar without issues, so a reducer may not be necessary when connected to a water supply with a pressure of 5 — 6 bar. However, it's important to check the specific requirements of your pressure washer model as mentioned in the instruction manual.
 |
| Scheme of connecting a pressure washer to the water supply using a check valve. |
The hose is connected to the faucet (or a check valve, if used) on one end and directly to the inlet fitting of the pressure washer or the filter attached to it on the other end. The filter can be integrated into the design of the pressure washer or provided as a separate part in the kit. Its purpose is to capture fine particles like sand, rust, and other impurities that may be present even in relatively clean tap water. It is strongly recommended not to connect a pressure washer without a filter, as even microscopic impurities in the water can cause premature wear or damage to the pump's plunger components. If your pressure washer does not come with a filter, it is advisable to purchase one separately as an accessory. When connecting the hose to the pressure washer fitting, it is recommended to use a connector with hitchhiking functionality, allowing you to disconnect the hose without shutting off the faucet.
 |
| The pressure washer filter is designed in such a way that it is convenient to connect a hose with a connector to it. |
How to connect a pressure washer to a barrel?
Some pressure washers have a water intake function, allowing them to operate without being connected to a water supply. They have sufficient power to draw water from sources such as a cistern, barrel, bucket, inflatable or frame pool, pond, or lake. But it is worthwhile to understand that a high pressure washer is not a motor pump and not a pump for water supply. The device should be placed near the water source, and a short hose of no more than 1-2 m should be used to minimize hydraulic loss. The end of the hose that goes into the water source should be fully submerged, and it's advisable to attach a weight to prevent it from floating to the surface and drawing in air during operation. Before starting the motor, ensure that the hose is completely filled with water to avoid "dry running," which can be damaging to the pump.
When connecting a pressure washer to a barrel, the process is similar to connecting it to a water supply system. You should still use a strainer to capture any particles or contaminants in the water, and it's recommended to have a check valve at the end of the supply hose to prevent backflow.
 |
| By installing a fitting with a valve at the bottom of the tank, connecting a pressure washer to a barrel or rainwater collection tank becomes as straightforward as connecting it to a regular water pipe. |
What can be washed with a pressure washer?
Pressure washers are quite versatile devices that can be used to wash and clean various surfaces. It is only necessary to remember that for each task its own working pressure is selected (as a rule, it can be changed in a certain range using a regulator on the washer body or an adjustable nozzle). If the pressure is incorrectly selected, a jet of water with too much pressure can damage the surface to be treated.
Low pressure (around 20 bar) is suitable for washing off dust, fresh dirt, and light soil from various items such as football boots, roller skates or garden tools. When washing bicycles, a slightly higher pressure is used, but not at maximum power. It is important to avoid directing a strong jet of water at sensitive parts such as the the chain, cassettes, bearings, as these components should not be exposed to excessive water pressure that could wash away their lubrication.
 |
| The “before” and “after” examples show how effective pressure washers are when cleaning various surfaces. |
Pressure washers with a range of up to 100 bar are suitable for washing garden furniture, waste containers, lawn mowers and implements. For washing cars, motorcycles, scooters or trailers, devices with a pressure of up to 125 bar work well. Devices with a pressure above 150 bar are ideal for cleaning strong and hard surfaces like concrete, brick, stone masonry, tiles, and ceramic floor tiles.
What are pressure washer nozzles?
High-pressure devices can form jets of various shapes. The width of the "torch" (that is, the angle of opening of the water jet in the form of a "fan") is changed either by turning the tip (fan nozzle) or by replacing the nozzle. Replacement nozzles are standardized and color coded. Each of them has its own purpose and its own job:
- red 0 ° — point nozzle, which forms a very narrow "beam" and directs the entire power of the water jet to one point;
- yellow 15° — nozzle for removing stubborn dirt from solid surfaces, such as concrete, stone or cement pavers, which is used for paving paths;
- green 25° — universal nozzle for cleaning wood and painted metal (for example, a fence or a lawn mower deck);
- white 40° — nozzle with a wide and "soft" jet for delicate work, such as washing a car or window glass;
- black — nozzle for applying car shampoo or spraying water mixed with detergent.
 |
| Interchangeable nozzles with different jet widths. |
Manufacturers offer various accessories for pressure washers to enhance their versatility and convenience. Some examples include the "mud blaster" for tackling stubborn dirt, foam generators for thick foam application, washing and rotating brushes for car care, and Patio nozzles for cleaning large flat surfaces like wood terraces, concrete platforms, and floors.
How far away should a pressure washer be kept?
To avoid damaging the paintwork, glass, or rubber surfaces, it is recommended to use a fan nozzle with a minimum distance of 30 — 50 cm between the nozzle and the surface. This allows the water flow to disperse and reduce its force to a safe level for sensitive materials.
For tougher and more durable materials like concrete, the nozzle can be brought closer to the surface, maintaining a distance of 5 — 10 cm. This allows you to use the full power of the water flow generated by the high-pressure pump to effectively remove stubborn dirt.
 |
| Manufacturers of high-pressure washers recommend that when washing a car, keep the nozzle at a distance of at least 30 cm from the surface of the body. |
Can you clean windows with a pressure washer?
To clean window panes with a high-pressure cleaner, certain precautions should be taken. Reduce the water flow pressure to a safe level, similar to washing a car (around 100 — 125 bar). Avoid using nozzles with a narrow and strong jet, and opt for a fan nozzle with a wide spray angle or switch the universal nozzle to fan spray mode. Maintain a distance of 30 — 50 cm from the window while cleaning to ensure a gentler and safer water pressure.
Following these rules, you can safely clean delicate surfaces such as double-glazed windows, solar panels and roof collectors, and greenhouse glazing. Using a pressure washer is more convenient than alternative methods like a vacuum cleaner for windows or a window robot, especially for larger cleaning tasks.
 |
| Glass surfaces can be washed with a pressure washer if you act carefully and wisely. |
What is a dirt blaster for in high pressure washers?
The mud nozzle is used to remove stubborn dirt and caked layers of dirt from hard and durable surfaces. It is a rotary nozzle that forms a narrow and strong rotating jet. Due to the spiral movement, the flow of water continuously hits the same point from different directions. Therefore, the mud blaster can remove the most stubborn dirt and break up large clods of dirt — something that fan and point nozzles cannot do.
The mud cutter is considered a very powerful tool (sometimes even too much). It is not recommended to use it to wash the paintwork of a car or direct a powerful spiral jet onto glass and tires.
In slow motion, you can especially clearly see how the mud nozzle of a pressure washer works:
Can be the engine washed with a pressure washer?
Pressure washers can be used to wash the engine (as well as to remove dirt from other parts of the car: body, bottom, rims and tires). You just need not to overdo it with water pressure and protect some parts and components from liquid.
Before cleaning the engine and transmission it is important to take necessary precautions. Firstly, remove the terminals and disconnect the battery. Then, cover sensitive components such as the distributor, breaker, electronic control unit, fuse box, connectors, and car alarm parts with plastic bags to prevent water ingress. Instead of using active foam, apply a mild cleaner to the dirty areas using a hand sprayer and brush, allowing it to soak for 10 to 20 minutes. Once the dirt is softened, you can use a high-pressure cleaner with a wide jet (such as a 25° or 40° angle nozzle or a fan nozzle) from a distance of approximately 75 to 100 cm to rinse off the excess dirt.
 |
| High-pressure washers are commonly used to clean the entire car, including the engine compartment, in a comprehensive manner. |
Can fairy be poured into a pressure washer?
Dishwashing detergents are similar in composition to car shampoos. They also foam and can launder grease. Therefore, many owners of washers are tempted to pour the same agent that is used in the kitchen for washing dishes into the reservoir of a high-pressure cleaner and see how it copes with washing dirt on a car.
Practical experience with foam generators has shown that using household liquids like Fairy does not provide the same quality of foam as specialized chemicals designed for car washing. The foam generated from Fairy liquid tends to quickly flow down the surface instead of clinging to it, which limits its effectiveness in removing dirt. Dishwashing detergents, being formulated for dissolving fats on plates, pans and pots, are not as effective in removing ordinary dirt, let alone stubborn substances like bitumen and engine oil that commonly accumulate on car surfaces.
Using dishwashing detergent in a high-pressure washer is not recommended because it is less effective than dedicated car shampoos and lacks the necessary foaming properties. It will be less effective than the cheapest hand wash car shampoo (not to mention active lather), and you will still have to brush hard to mechanically remove road grime from the car body.
 |
| It is better to use those detergents that are recommended by the manufacturers of car washes themselves. |
Why does the pressure washer work intermittently?
Sometimes high-pressure devices work unevenly, with small jerks. As a rule, they manifest themselves in the fact that when you press the gun button, the pump starts, works for a while, and then stops for a few seconds. When the pump is turned off, the water flows in a thin stream without any pressure, after which the pressure returns to normal, and the jet again beats at full power.
The main reason for the pulsating pressure during the operation of a high-pressure washer is often attributed to low voltage in the power supply network. Many modern models, such as Karcher products, are highly sensitive to this factor. When the voltage drops below 210 V, the pump is unable to work at its full capacity, resulting in insufficient water flow. As a result, the pump's outlet valve closes momentarily, causing the pressure to fluctuate. Using a with a stabilizer an help address voltage issues in the mains.
But there are other reasons for jerks in the operation of a high pressure washer:
- airiness — air in the inlet pipe or hose leads to the formation of bubbles and air pockets that prevent the pump from working;
- clogging — it can occur when dirt or debris accumulates in the nozzle, obstructing the flow of water. This restricts the nozzle's ability to pass the full amount of water supplied by the pump. Similarly, if a nozzle with a smaller cross-section than required or a non-compatible jet tube is used, it can also result in reduced water flow and pressure;
- lack of water — due to a valve not fully open on the tap, a pinched hose, or contamination of the fine filter, less water is supplied to the pump than it needs to work;
- valve wear — the pistons on the bypass valves are worn, causing them to not fit snugly against the seats. The issue is solved by replacing the valves or rubbing them to the seats with an abrasive paste;
- pressure valve malfunction — a breakdown or weakening of a miniature spring in the valve responsible for normalizing pressure and turning off the motor leads to a partial inoperability of the device. In such cases, repair with replacement of the spring is required.
 |
| Professional pressure washers like Kranzle are more reliable than household devices. But their price is also much higher. |
How to drain water from a pressure washer?
After finishing the work, completely drain the water from the pressure washer. This must be done in this order:
- turn off the motor and disconnect the hose that supplies water to the washer;
- press the pistol lever to release the residual pressure in the pump, and wait for the characteristic “snorting” sound;
- disconnect the high pressure hose from the device;
- turn on the device for a short time (10 — 20 seconds is enough) so that the pump expels all the water from the "insides" of the sink through the outlet.
Can high-pressure washers be used in winter?
It is quite possible to use a high-pressure washer in winter, if immediately after work, without delay, drain all the water from the pump and put the device in a dry and relatively warm room.
Car washing in winter is less effective compared to summer due to the thickening of car shampoos and active foam in cold temperatures, resulting in reduced foaming. Additionally, it is important to note that automakers advise against using water to wash a car when the air temperature is below -20°C as it can potentially harm the paintwork of the vehicle.
How to store a pressure washer in winter?
To ensure proper storage of a pressure washer, it is recommended to keep it in a dry location at temperatures above 0°C (as frost damage is not covered by the warranty). Before storing the device, it is important to drain all the water from it and clean the filters and tank to remove any dirt or detergent residue. The housing should be wiped dry, and the high-pressure hose and power cable should be coiled without any kinks. Applying silicone grease to joints, connectors, and O-rings can provide extra protection during winter storage.
 |
| Water turns into ice in winter, which can literally tear apart not only a plastic jet tube from the inside, but also a metal pump of a pressure washer. |
Instead of an afterword
When choosing a high-pressure washer for use in a garage, private house or country house, use the pressure washer catalog, which contains almost all models that are currently on sale in online stores. You may also find useful articles with selections of TOP-5 pressure washers in various "nominations", "weight categories" and price segments.
Articles, reviews, useful tips
All materials
