Filling two tanks with a fire hydrant

Clear Shine

New member
While I'm building my new trailer setup, trying to map out the best way I want to fill my (possible) two tanks. I already have a 300 gallon leg tank along with looking at getting a 500 gallon tank. I already have my way set up I am going to fill them (top fill with an air gap), but do I want to only fill one via the hydrant and have a 2-3" line connecting the two at the bottom? Or do I want to try to rig something up to top fill both of them? I don't know if anyone has done this or you physics guys have any suggestions?
 

Clear Shine

New member
You might want to set up a back flow protector on the hydrant. I had to to be able to use the hydrant in Virginia

Lenny, I would have a back flow preventer by having an air gap in the hydrant dump. I was trying to fill up both with one 2" line. My physics thinking is if I have the hydrant line with the air gap over the 500 gallon tank and have a 2-3" PVC line connecting the tanks at the bottom, the water will rise to meet the level of the big tank by equaling them out? I may be wrong in my thinking.
 

Scott Stone

New member
Lenny, I would have a back flow preventer by having an air gap in the hydrant dump. I was trying to fill up both with one 2" line. My physics thinking is if I have the hydrant line with the air gap over the 500 gallon tank and have a 2-3" PVC line connecting the tanks at the bottom, the water will rise to meet the level of the big tank by equaling them out? I may be wrong in my thinking.

The only problem I can see is that the 2" lower line will nt keep up with the line feeing the tank that is under pressure.
 

Steven Button

Administrator
I would consider going with the 2 fill lines - I'm not a physicist, but if you went with a large diameter connection pipe that could keep up with inlet flow... when you reach the top of the 300 gallon tank, and there is 300 gallons in the 500 gallon tank, will the smaller tank not start to overflow beyond this water volume?

Unless, of course, the 300 gallon tank lid is water tight.
 

Clear Shine

New member
... never mind, you could put a valve on the connector line! doh!

I thought of both of those already too. My thoughts were keeping the lid on the 300 gallon, fed over with a 3" line connecting to the 500 gallon tank. I would have an inline ball valve to shut off the water when it's full and also have that 3" line T out to feed the machines (eventually choking them down to 1" lines). When the water gets around 250 gallons, you open the ball valve. Also, I would only run the inlet supply line (Hudson float valve 3/4") to the 500 gallon and make the tanks even out on their own on a big resi job. Anyone see a flaw in my plan?
 

Christopher

Moderator
When one tank is physically taller than the other, You would have to block the flow to the shorter tank so it does not over-fill.

Having an equalizer line 2" or 3" between the two will help the shorter tank over-fill unless your top lid is air-tight which they hardly ever are or we all would have problems using them for pressure washing when pulling water out of them. Have you ever noticed that even with the top lid tight, air still gets into the tank so you can keep on pulling water? If it was air tight, the pressure washer would starve for water eventually. Because of this air leak, the tank will over-flow from the taller tank via equalizer line once the taller tank water level is higher than the shorter tank.

To have the best of both worlds, you might have to put a ball valve on the equalizer line (to block the shorter tank when full to keep it from over-flowing) and possibly a couple ball valves to the fill lines, think of a "T" with a ball valve on each of the shorter sides so you can block off the shorter tank while keep filling the taller tank. Block in the equalizer line when the shorter tank is full or keep it blocked and just use the fill valve to the shorter tank when the tank is full then when the taller tank is full, just block in the meter or hydrant.

This way you can fill both tanks all the way and not over-fill them and when the taller tank is level with the shorter tank, open the equalizer line so you are pulling out of them equally until they are empty. With garden hose lines filling them both or just one of them, the equalizer line will keep them level.

This is what I would do if I was in that situation which I might be before the year is over for a particular use.

Hope this helps
 

greg/sd

New member
I use to have dual 275 gallon totes on a flatbed trailer steup with hydrant hookup to one tank and gravity flow to the other. lt would take about 5 mins to equalize the level of water after filling never could use the full capacity without over flowing one tank. drop fill for both will work the best.
 

Clear Shine

New member
I use to have dual 275 gallon totes on a flatbed trailer steup with hydrant hookup to one tank and gravity flow to the other. lt would take about 5 mins to equalize the level of water after filling never could use the full capacity without over flowing one tank. drop fill for both will work the best.

Greg, what size connector line do you have between the two?
 

greg/sd

New member
I had two inch pvc hooked to the bottom openings on both tanks the hookup for the hydrant was closer to one tank so that one filled the quickest. It worked well but you would only end up with about 525 gallons when done filling. still very quick way to fill your tanks it took about 8 to 10 mins to fill up and be on my way.
 

"Red"

Graphic Designer
Just some food for thought.

Top fill the 500. Have an overflow (near the top) on the 500 into the top of the 300. Feed your pump(s) from both tanks at the bottom combined via a 'Y' (with shutoff valves). You can start using the 500 right away while the 300 fills up. The overflow from the 500 will fill the 300 without overflowing the 500. Plumbing should be large enough to allow full hydrant flow through the 500 into the 300.

Shut off hydrant feed when both tanks are full (and back on as needed). Feeding from both tanks simultaneously allows you to empty both tanks during use so you won't be hauling around the excess weight after the job (or have to dump it). If I remember correctly, you're paying for that water from the hydrant, so why take more than you need just to end up dumping it later. If hauling it to the next job is not a problem, then don't dump it.
 

up-power

New member
I have 2 totes plumbed together using 2 inch PVC. If you fill up with a hydrant 1 tank will fill in 2 minutes but the other has to gravity push to even out. It's not fast enough to keep up. I fill one with hydrant and then to the other tank to fill it.
 

Christopher

Moderator
Not too many jobs have a hydrant right next to the job so you have to move to the hydrant to fill then go back to the job.

If you fill from a hydrant to start the job and have a garden hose filling when working, that gives you additional time before you run empty.

When running 2 or more machines, the larger capacity of water storage helps a lot, especially when you only have 1 hose to fill with besides the hydrant.
 

Tony Shelton

BS Detector, Esquire
I'm glad you guys are here. I would have never thought that a 2 inch pipe couldn't keep up, but it makes sense.

See, you guys saved me again.
 

Clear Shine

New member
I am actually now contemplating only running only one 500 gallon tank to eventually run up to four 8gpm machines at one time. The only time I would ever use all 4 machines at one time would be at apt complexes or a big commercial jobs where I will have lots of hydrants easily accessible. In fact, the one complex I am bidding on that I would use 4 machines has a hydrant every 200 ft. I also can fill a 500 gallon tank in under 2 minutes, so every 15 min, ill have someone fill up the tank. It's just not worth having two 500 gallon tanks for the few jobs I would benefit from it. I also have access to a 1500 gallon water wagon if needed too.
 
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