Simpson MSH3125-S Pressure Washer Review

The Simpson MSH3125-S is what we consider the gold standard of residential pressure washers. It’s built to last with high quality components, and it delivers plenty of cleaning power for any project you’ll have at home. It’s not the cheapest option, but it’s the best value for your dollar by far.

Man using the Simpson MSH3125-S gas pressure washer


Use the table below to get an overview of the Simpson MSH3125-S. Our review will take a closer look at how everything works, but this should give you an idea of what to expect in terms of cleaning power, features and more.

Brand Simpson
Model MSH3125-S
Type Gas
Use Residential
Engine Honda GC190
Horsepower 5.2
Fuel tank 0.475 gal.
Pump Axial
Pressure 3,200 PSI
Volume 2.50 GPM
Cleaning units 8,000.00
Frame Steel
Wheels 10.0 in.
Hose 25 ft.
Wand 16.0 in.
Nozzles 0°, 15°, 25°, 40°, soap
Detergent Siphon
Dimensions 34.0 x 21.0 x 24.0 in.
Weight 65.0 lbs
Warranty 1-5 years
MSRP $398.00


The MSH3125-S can be unboxed and ready for use in about 15 minutes. It does require some assembly, but most of the process is standard for any gas pressure washer. You don’t need any tools, but you will need about a half gallon of gas.In the box, you’ll find the following items:

  • (1) Simpson MSH3125-S gas pressure washer
  • (1) MorFlex high-pressure hose (25 ft.)
  • (1) Rear-entry spray gun
  • (1) Steel wand (16”)
  • (5) Quick-connect nozzles (0°, 15°, 25°, 40°, soap)
  • (1) Detergent siphon
  • (1) Simpson premium engine oil (10W-30)
  • (2) Hand knobs

The pressure washer comes out of the box in two pieces: the base (which holds the engine and pump) and the handle. Once you remove all the packaging, the handle simply slides onto the lower part of the frame and secures into place with the included hand knobs.

From there, the accessories can be unwrapped and put in their appropriate places in the dashboard at the top of the handle. The hose hangs on the left, the spray gun clamps on the right and the nozzles are held in a series of rubber grommets in the middle.

The only thing left to do is add fuel and oil to the engine. You have oil thanks to the pint included in the box, but of course, you will need to supply your own gas. Before starting the engine, remember to prime the pump. You can read more on this in our tutorial on how to use a pressure washer.


The MSH3125-S delivers 3,200 PSI at 2.5 GPM, which is considered on the higher end of cleaning power for a residential pressure washer. It’s not much higher than other gas units (the average is 3,000 PSI), but it’s noticeably higher than an electric unit (these average around 2,000 PSI).

Simpson MSH3125-S gas pressure washer

Simpson MSH3125-S

The MSH3125-S has a 90% recommendation rate (based on 5,000+ verified reviews from six sources). It’s the best-selling gas pressure washer at Amazon and Pressure Washers Direct, and it’s top three at Home Depot and Lowe’s.

With this much power, you can clean just about anything: houses, driveways, decks, cars, etc. You should have no problem with harder projects like stripping old paint, but if you find yourself in a tough situation, you can always inject detergent into the stream for some help loosening materials at the surface.

Regardless, what’s important here is how you get this performance: a Honda GC190 engine and an axial cam pump from OEM Solutions. The GC190 is Honda’s best consumer-grade engine, and it has a strong track record of reliability. The pump doesn’t have the same public reputation, but it’s also a good choice because OEM is Simpson’s sister brand, so they ensure quality control.

The engine will run for about an hour on a full tank of gas, possibly two depending on your usage. It’s not too loud (Hondas are known to be quieter), but at the end of the day, it’s still an engine, so expect some noise.


The MSH3125-S may be a residential unit, but it’s built to the same standards as Simpson’s commercial pressure washers. The frame is made of welded 16-gauge steel, and it rolls on heavy-duty 10” pneumatic wheels. It’s a few pounds heavier as a result, but it’s also much easier to maneuver, especially on uneven terrain like gravel or grass.

Similarly, the included accessories are nicer than most others. For example, the hose is braided and all the fittings are brass. There’s one downside, only one is a quick-connect fitting (at the end of the wand for the nozzles), but at least it’s the one that matters. You can always get adapters for the rest.

Detergent is injected using a siphon, which some people consider less convenient than an onboard tank because you have to use your own bucket to hold the solution. This can be a matter of preference, but generally, siphons are actually easier to use and don’t require as much cleanup.

Compare similar pressure washers

Use the product carousel below to compare the Simpson MSH3125-S to similar pressure washers based on things like cleaning power, features and more. For more alternatives or for help choosing, read our guide to the best pressure washers.

Simpson MSH3125-S gas pressure washer

Simpson MSH3125-S

  • 3,200 PSI and 2.5 GPM
  • Honda GC190 engine (6HP)
  • OEM Solutions axial cam pump
  • 25 ft. hose, 16″ wand and 5 nozzles
  • Detergent injection via siphon
  • Warranty varies by part (1-5 years)
Ryobi RY803001 gas pressure washer

Ryobi RY803001

  • 3,000 PSI and 2.3 GPM
  • Honda GCV160 engine (4HP)
  • Axial cam pump
  • 35 ft. hose, 20″ wand and 5-in-1 nozzle
  • 128 oz. onboard detergent tank
  • 3-year warranty
Generac 7122 gas pressure washer

Generac 7122

  • 3,200 PSI and 2.7 GPM
  • Generac engine (196CC)
  • Axial cam pump
  • 30 ft. hose, 20″ wand and 5 nozzles
  • 64 oz. onboard detergent tank
  • 3-year warranty