Is anyone using drums or barrels as holding tanks... focusing...
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Eugene Oregon.
Daily, dozens of junk RecreateVehicles are towed off the streets to dismantlers (aka wrecking-yards).
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If I was me, I might stroll around a dismantlers.
After the siding is recycled off a factory RecreateVehicle, all the innerds are visible.
I might acquire suitable holding-tank candidates from a factory RecreateVehicle.
They are engineered to contain your entire life-savings, they also have the proper fittings and straps.
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For reference, I usually estimate the gallon weight of any fluid at around 8#/4kg per.
With its container, we can call it 10#/5kg a gallon.
Multiply by fifty-five gallons.
I think I would want that to not go flying during a sudden stop.
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Soaked and saturated in nature's bounty, I fully understand if the responding ambulance crew triage me as a 'lost cause'... and encourage me to walk to the hospital under my own power.
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[edited to add]
What are you thinking for holding your holding-tanks during panic-swerves and bouncing over a topés ('dead cop') in Mexico?