Buffer Tank for 5.5 gpm?

I just got my first real machine today. I went for a 4gpm with 4000psi but ended up getting a 5.5gpm with 3000psi. The people at the shop said that a tank wont be necessary unless Im dealing with well water. Is this the case? I was under the impression that anything over 4gpm needed a buffer. Can I run a 5.5 straight from a house without starving the pump?

Just go ahead and get one. You’ll want to upgrade sometime. It just depends on the water supply in your area. Shoot, sometimes I think some houses around here will keep up with my 8gpm

Its best to have one even on a 4gpm. Even if most of the house in your area run 6 plus gpm from the spigot, that one house that doesnt will burn your pump. You really only need a 50 gall buffer for a 5.5 at least in my area.

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…until someone decides to take a shower or run the washing machine…

Best to have the tank. Run your unloader bypass back to the tank and you’ll always have cold water running through the pump. It’ll last a lot longer and you don’t have to be anxious when you’re off the trigger for a few minutes.

50-60 gallons should be plenty of capacity.

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I am debating between a 65gal leg tank from TSC or a used 135gal. The 65 is preferred because of its size, would most people say 65gal is enough for a 2500 5.5gpm machine? This is my first trailer build and I can’t tell you the water flow in my area because I don’t know.

Thanks for the input!

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I would go with the 135

65 is perfect. I run 2 8gpm machines on each truck and my biggest tank is 125 gallons. One is only 65 gallons.


I think it depends a lot on how many customers will be on well water, and how many on municipal supply. But most wells will keep up enough for house washing with a 5.5 machine.

If you were anticipating doing a lot of flatwork (which I’m guessing you’re not because of your choice of PW’er) on wells, I would go for the larger tank.

But if you guess that 50% or more of your customers will be on municipal supply, and you’ll really only be doing house washes, go with the smaller tank.

@Innocentbystander has the relatively unique situation where he can hook up to a fire hydrant at all the properties he services. It’s honestly not realistic for most guys to try and run 16gpm off a 65 gallon tank :face_with_monocle:


Thanks all.

I’m hoping I can do flat work as well. Let’s say atleast 50% is in municipal and 50% is flatwork, assuming it works out for me. You’d go with the 135?

I’m finishing my pick up (for now) build and went with a 35 gallon tank for a 5.5 2500 machine. I tested the flow out of the tank and got 5 gallons in just over a minute. Did the same test with just the garden hose and the results were about the same.

Am I asking for trouble here or is this adequate water supply?

I’ve read the belt fed machines will pull water from the tank. Is there enough pull to compensate for the flow being slightly below 5 GPM?

I’m also working on the plumbing for the bypass back into the tank.


35 gallons is on the smaller side for a 5.5 machine. Not every spigot you hook up to will be giving you 5 gpm. Some will only put out 2.5. Really depends on whether the majority of your jobs will be on town water or not. But even then, differences in plumbing and elevation can cause a shortage of flow.

Since you’ve already got the tank, you could give it a shot for awhile and see how it goes. Just keep an eye on it.

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Thanks! I will do that. I’m kicking myself for not getting the 65.

Wow, really? I have 225 gal for smaller machines and feel like there are times we run through water on flat work jobs. Any advice on how you make that work? Seems like I am missing something.


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I never once saw my 55 get below 2/3 with flatwork and my 5.5. Then again nobody is on well here so…