How does a pressure washer work?
A pressure washer uses a motor or engine to drive a pump that forces water through a narrow nozzle at high velocity. The pump takes in water from a supply line and pressurizes it - typically between 1,000 and 4,000+ PSI - before directing it through a hose, gun, lance, and nozzle. The high-velocity stream removes dirt, grime, grease, and other contaminants from surfaces. Hot water units add a burner and heat exchanger (coil) to raise water temperature before it exits the nozzle, which dramatically improves the ability to cut through grease and oil.
What is PSI and why does it matter?
PSI stands for pounds per square inch and measures the pressure of the water stream. Higher PSI means more force applied to the surface being cleaned. PSI determines how effectively the machine can break the bond between dirt and a surface - especially hardened deposits, paint, and scale. Light-duty residential tasks typically require 1,500–2,000 PSI. Commercial and industrial cleaning generally calls for 2,500–4,000+ PSI. Using more PSI than a surface can tolerate can cause damage, so nozzle selection and standoff distance also matter.
What is GPM and why does it matter as much as PSI?
GPM stands for gallons per minute and measures the volume of water the machine delivers. While PSI breaks the bond between dirt and a surface, GPM flushes debris away and determines how quickly you can cover an area. A machine with high PSI but low GPM will clean slowly and may leave residue. Professionals prioritize machines with 3.5–5+ GPM for efficient large-area cleaning. The product of PSI × GPM is sometimes used as a general measure of cleaning power (called Cleaning Units).
What is the difference between a residential and a commercial pressure washer?
Residential (or hobby) pressure washers are designed for occasional homeowner use - washing cars, patios, or siding a few times a year. They use lower-cost components and are not built for daily or continuous operation. Commercial pressure washers, like those Alkota manufactures, use industrial-grade triplex pumps, heavy-duty engines or motors, reinforced frames, and professional-grade seals and valves. They are engineered to run for hours every day for years. If you are cleaning for a living or operating in a demanding environment, a residential machine will not hold up.
What should I consider when buying a pressure washer for my business?
Key factors include: the type of soil you are removing (grease and oil require hot water), the surfaces you are cleaning (delicate surfaces require lower pressure and wider nozzles), how frequently you will use the machine (daily commercial use demands a commercial-grade unit), your power source availability (gas, electric, or PTO), your water supply situation (flow rate and pressure), and whether you need portability (skid, trailer, or wall-mount). Alkota can help you spec the right machine for your application.
What is a Cleaning Unit (CU) and how is it calculated?
A Cleaning Unit is an informal measure of a pressure washer's overall cleaning power, calculated by multiplying PSI × GPM. For example, a machine producing 3,000 PSI at 4 GPM has 12,000 Cleaning Units. It is a useful comparison tool when evaluating machines of similar configurations, but it does not account for water temperature (hot water is significantly more effective on grease) or chemical application. Use it as a starting point, not a definitive specification.
What is the difference between gas, electric, and diesel-powered pressure washers?
Gas-powered units are portable and high-output, making them ideal for outdoor field work without access to electrical power. Electric units are quieter, require less maintenance, produce no exhaust, and are well suited to indoor wash bays and facilities with reliable power. Diesel-powered units share the portability of gas but offer better fuel efficiency and durability for heavy continuous use, and are common on trailer-mounted rigs. Each power source has trade-offs in cost, maintenance, exhaust, and portability.
Can I use a pressure washer for food service or food processing applications?
Yes, but with important caveats. Food processing environments require NSF-listed detergents, stainless steel components where food contact is possible, proper drainage systems, and strict attention to chemical concentrations and rinse protocols. Hot water is almost always required to meet sanitation standards in food processing facilities. Alkota equipment is used widely in food processing, agriculture, and commercial kitchen applications. Consult Alkota to ensure your machine and chemical choices are appropriate for your specific food safety requirements.
What does 'cold water' vs. 'hot water' mean when shopping for a pressure washer?
A cold water pressure washer delivers water at ambient (unheated) temperature. It is effective for removing dirt, mud, sand, and loose debris, but struggles with grease, oil, and animal fat. A hot water pressure washer heats water through a burner and coil assembly before it exits the nozzle - typically to 140–200°F or higher. Hot water dramatically accelerates grease and oil removal, reduces detergent usage, and is the professional standard for any application involving petroleum-based soils.
How do I know what size pressure washer I need?
Start with your cleaning application. What are you cleaning? What is the soil type - loose dirt, grease, heavy scale? How large an area do you need to clean and how quickly? What surfaces are involved - concrete, vehicle paint, food processing equipment? Answering these questions guides PSI (how tough is the soil), GPM (how fast do you need to clean), and temperature (does grease removal require hot water). Alkota's team can help you select or configure the right machine once you know your application requirements.