Flat work and multiple machines

Greetings, part of our deal is we power wash 4-6 parking lots per year 15-50k square feet. Right now we have a 4/3000 power washer and a 16" surface cleaner. Then we rent whatever is available and normally that is 3.5/3500 from a big box store. So we have two machines running. Due to the fact we sometimes piecemeal the parking lots over 3 days renting is a pain.

I have a budget of about $2k. We do not have room for a big buffer tank so it pretty much needs to be what a commercial building can provide for water. Also not skid mounted. Here is the two ones we are looking at:

4/4200 w/ Honda 390 and Cat pump built to Dewalts specs


or Karcher 5/3000 w/Honday 390 and Karcher pump- belt drive

The Karcher is a bit more than the budget but if there is a good enough reason we can swing that. Would there be any good reason we might need that extra 1200 psi doing parking lots?

Thank you for your thoughts.

Sounds like you’re on the right track. Don’t waste money on that karcher. I’d go with a couple of electric models. Don’t let someone persuade you to spend that kind of money on equipment. 2.5 GPM is plenty.


So what you’re saying is you want to drive 100 mph on a pedal car right?

Dang they’re trying to get $5800 for a 5/3000 v-twin. What the heck.

Im at a loss for words. Only thing i can think to say is use the search bar. Maybe let a company that knows what they are doing get the job, watch them and try to copy them next year. Lol. Although im betting they have spent considerably more than 2k on a set up

Power washing is not our main job. It is just something we do a few times a year. We have been doing this for years just with rented equipment that sometimes is not very good quality.

It’s more the technical questions. The CAT pump on the DeWalt is basically a 3.1 gallon standard CAT they modified to put out 4 gallons per minute. Is there a longevity issues with that?

Is there a big enough of a difference between 4/4200 over the 5/3000 to make it worth extra money?

Only work ever done with it will be concrete parking lots in conjunction with a second power washer that is 4 gallons per minute at 3,000 PSI.

Most people that post here, it’s what they do for work. And many just with one main machine. We just want a good quality job, that doesn’t take forever and can fit within our limitations on the size of machine.

The most cost effective and productive option you have would be to either invest in a full trailer with 1 or 2 8gpms and a hotbox or contract the job out to a company with the right equipment and take 40%. You don’t have any business cleaning a commercial parking lot without hot water and a commercial machine. It’s a disservice to your time and the customer’s money.

There’s not enough money in the world for me to clean a parking lot with a 3.5 gpm lol

1 Like

That should answer your question

The Honda GX390 for an engine is a good choice. Most of us here will recommend a belt drive or a gear box instead of the direct drive. The direct drive won’t last near as long. And if you ever go with a buffer tank, direct drives are near impossible to get to work with buffer tanks.

If you don’t want a buffer tank, you’re limited to about 4gpm. Customer spigots won’t put out much more than that on average. And if you tried to go with more than 4gpm, and ended up with a spigot giving you less than what you need, you’ll starve the pump and ruin it.

He does parking garages.

Correct. And his current set-up requires a spigot regardless of what he’s washing.

I meant to delete that, he does parking lots. But the garages typically have really good water flow with all that fire suppression plumbing.


I think most garages, at least the few I’ve done are dry systems. When the fire department gets there they pressurize the system with water.

Most buildings we go to have two spigots. There’s only been one building that just had a single spigot, then we just tied into the irrigation system to pull water for the second machine.

I’m leaning toward the 5 gallon per minute, just because it’s belt drive and more GPM. Suppose I could set up a little 20-25 gallon buffer tank. At most would be pulling 9 gallons per minute between the two machines. Most every commercial building should be able to handle that.

Wherever you’re working, I’d go and check it and be sure you have the necessary flow. Otherwise, without a buffer tank, you’ll ruin your pump if you don’t have the necessary gpm.

And without a buffer tank, you’ll be limited in using it in other settings. Remember, all it takes is using it without the needed gpm just once, and you can damage the pump.

I did a commercial job earlier this year for a major company. Thankfully I showed up with a full tank of water b/c at best they had 3 gpm coming from the hook-up.

It may put out X gpm, but is will be drastically reduced after a few hundred feet of garden hose, plus if hose is going at an incline etc.

Buy once, cry once. Get what you need to do the job right and you’ll never be sorry.

1 Like

What is the output on those spigots? If you insist on keeping on, then you’ll want to know that info. And on the multi-spigot places, you’ll probably want to know what it is with them both/all putting out at the same time.

We will be adding GPM readings w/both spigots running to our precheck list.

Appreciate the input it has helped to clarify the details we were missing.

Whole different animal. I do several garages and water flow decent, but usually not great. Maybe 6-7 gpm.