Buffer tank requirements

Newbie looks to start a build. Local shop says that a 125g buffer tank isn’t enough for their 7gpm machine they sell. I see many say don’t travel with water yet I would think with a big tank and a 7gpm if you arrived with none you would be waiting a while for it to fill.

I see mixed posts on this. Would like to know what size tank is a safe bet for this when using residential spigots.

Also told ibc totes are inferior to leg tanks yet see many use them, agree or disagree.

What are the spigot flow rates in your market area? That’ll be key in determining whether 125g is sufficient or not.

Been told they are 3.5 -4 gpm. My house which is a good reference for the area is about that.

It’s up to you, you know what type of work you’re going to be doing. If your tank is 1/2 full, you have about 20 minutes until you run out, 40 minutes if it’s full. Is that sufficient for what you’re doing?

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Residential house wash and driveways (most driveways here are large)

Assuming it’s calculation based on trigger time but since I never used a 7gpm don’t want to rely on math and assumptions.

I’m thinking a 225 tank maybe 1/2 full and filling on arrival would work or how could others ever be doing it since most say don’t travel with water?

The 7gpm is on sale for less than their 5.5 and with a better pump (general be comet).

I use a 275 tank and it’s usually somewhere from emptyish, to 1 or 2 metal l bars high with water. I hook up first thing and set up then run my machine. I still find myself waiting on water to fill depending on what I’m doing. It’s annoying but I don’t have the capacity to have the thing be full and roll around with that so it is what it is. I find myself going at a slower pace with some stuff just to make the time off the gun longer to help build water.

What size machine are you using? Sounds like you’re using a tote tank, any issues using that over a leg tank?

I run an 8 gal off of a 100 gal tank. I only drive with 20 to 30 gal in it and the first thing i do when i arrive at a property is hook up the water. It sometimes fills up before i even start. When im house washing the tank is usually not a problem but when im surface cleaning i will have to wait. To me its not that big a deal considering i was using a 4 gal machine for the previous 7 years. Never had to wait on water but the time im saving with the more flow more then makes up for waiting 10 minutes sometimes. It also provides an opportunity to get some water for yourself or make a phone call or whatever you can find to occupy your time

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That helps. Was wondering if I should get the 5.5 over the 7 even though the 7 is on sale for less. Seems like even if you have to wait on surface cleaning it still works in your favor.

I run a 8gpm off a 55 gallon vertical tank. The float valve is installed in the lid and the bulkhead draws right to the bottom, so I get the full 55 gallons of buffer capacity. I usually drive with it 1/4 - 1/2 full, and have corrugated drainage pipe in it to cut down on sloshing.

I have to wait a bit for water on around a third of the wells I draw from, and maybe 5% of the municipal-fed homes due to poor plumbing or higher elevations.

Occasionally I will throttle the machine down to 5.5-6gpm, but most of the time it’s not a major inconvenience to just wait a few minutes.

It’s important to note that I do primarily house washes (flatwork is pretty rare in my market). And I have a water trailer that I will use if I get a really large house on a well, or a lot of flatwork (I did a tennis/sports court last summer that would have probably dried the customer’s well had I not brought my trailer).

Good real world info, thanks. Seems like a 225 tank would be ok and either I have to drive with some and or just wait a little bit for catch up on flat work.

Being the 7 gpm with a comet pump is cheaper than the 5.5 with a general pump, I don’t see any reason not to go with the 7, agree?

Original plan was for a 5.5. I could always go with a 4/4 but seems to make sense to go up if finds allow.

I run 6.8 gpm with a 30 gallon buffer tank. My supply hoses are 3/4 inch Flexzilla in 50 foot sections that don’t run through the reel. I roll off what I need to get started & if the pump cavitates one time I’ll hook up a second supply hose to another spigot. I’ve got 2 Topaz float valves & I never have to wait for water. 95% of the time, one spigot is enough. Also, the trailer pulls the same whether the tank is full or empty.

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You have a photo of your rig build showing the smaller buffer thank? I have the idea to build a small cart based unit with a smaller buffer tank in this size range as you have, and am looking for ideas and feedback. Thanks.

I have 225 for my 8 gpm….do a lot of flat work, works out great. Dual feed it when I have low water…not often though.

I have a 55 gallon vertical tank with my 8gpm.

Keep in mind unless you are doing constant flat work, you won’t be on trigger all the time so even a 4gpm spigot won’t be that bad. I had a job yesterday with low flow and I just had my helper run a second hose from the other spigot.

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I have an 8 GPM with a 330 gal tote. I do commercial and residential and when doing a lot of flat work I can run the tank dry if I stay on the trigger. Moving things, grabbing a drink, etc allows the tank to catch up so I don’t notice it that often when I’m connected to a water source. On some of the commercial work, and when I wash away from water sources (fences on large pastureland, large driveways/cement areas and places that don’t have external water connections) I have to fill via a fire hydrant and with my 24” surface cleaner I get about 40 minutes of continuous on trigger before I need to go fill up again. But as I said, moving hoses or items or switching off of the SC lengthens the amount of time between refills. If I show up with 1/4 tank full and do say a housewash, I can start immediately (I always connect to water first) and by the time I’m halfway through a medium size house the tank will fill up. (3-5gpm feed from house). When I switch on and off between say a roofwash/housewash/flatwork the tank will stay about 1/2 full so about 150’ish gallons. I used a 4gpm washer past two years - bought the 8gpm this past January so although I’ve washed a lot with it already, I’m still trying to get more efficient with leaving with about 100 gallons or less. In my case, the tote comes in handy for the places I wash that require me to use a hydrant for my water source. I have two Hudson valves - one of them is set for about 175 gallons which is great for subdivision work where I may have a couple of houses near each other (prevents me from jumping in the truck and driving 300 gallons around because I overfill). I find that 175 gals is about right for my methods with a combination of roof/house/flat work with a residential feed using the 8gpm machine.

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The biggest consideration for the size tank you will need is likely the average flow you will be able to get from your water source.

Im spoiled down in south louisiana and the average flow here is well over 10 GPM from a residential household spigot.

The next factor to consider is the length of supply hose as this can drastically affect the flow into your tank. I run a 3/4 inch flexzilla, and 100 ft gets 95% of my jobs from the curb to the closest spigot.

The only time i have ever been short on water supply for my 8 GPM is when i was about 15 feet short for my 100 ft hose and instead of rolling off the next 50 foot section i have, i just hooked up to the customers hose already connected to the spigot. This added atleast another 100 ft and since it was 5/8, and i left it mostly coiled up near the house, caused me to get much less than 8 GPM. Thats when i realized length, diameter, and flow from the spigot are all factors to consider.

If you are in an area where elevation, long 100+ feet driveways, and low flowing well water supplies are common, a larger tank will be better. This is where the term buffer comes in to play. You are buffering the supply.

If you are looking to buy a water tank, taller with less footprint will also allow you to draw down lower before bubbles and turbulence become a problem for your pump. This will also allow you to carry less water with you, 18 -24 inches minimum above your bulkhead. Meaning you can wait less and start sooner, if efficiency and time management are your goals and weight is a concern.

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i use a 65g buffer tank with my 7gpm and it’s never a problem. sometimes the water will deplete only if the spigot is especially slow. but once it fills up, it will almost always last long enough to finish the job.

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Thanks for all the real world answers. Puts my mind to ease that I can work with the 7gpm and reasonable size tank.