I've seen a few food-grade barrels bulge over time, usually from thinner walls or improper venting. If you're setting up new barrels, make sure you've got a solid overflow system—keeps pressure down and prevents surprises during heavy rains. Those car wash drums do sound promising though...might have to look into those myself.
Good call on the overflow system—definitely something you don't want to overlook. I've seen barrels deform even with thicker walls, especially if they're placed in direct sunlight. Heat can really amplify pressure issues, so consider shading your setup if possible. One thing I'd add is to make sure your overflow pipe diameter matches or exceeds your inlet pipe size; otherwise, heavy downpours can quickly overwhelm the system.
As for the car wash drums, I've used them before and found they're generally sturdier than typical food-grade barrels. Just be cautious about thoroughly rinsing them out first—some detergents leave residues that aren't great for plants or soil health. A good rinse with vinegar and water usually does the trick.
"Heat can really amplify pressure issues, so consider shading your setup if possible."
Good point about shading—I've noticed the same thing. Last summer, I had a barrel warp pretty badly after just a few weeks in direct sun, even though it was supposedly heavy-duty plastic. Ended up building a simple wooden enclosure around it, and that solved the issue completely.
One thing I'm curious about though: has anyone experimented with adding filters or screens to their overflow pipes? I've been thinking about debris buildup during storms—leaves, twigs, and stuff like that—and wondering if it's worth installing some kind of mesh or filter system. My concern is that it might slow down water flow too much during heavy rains...but maybe there's a good compromise out there?
Good point about shading—I've noticed the same thing. Last summer, I had a barrel warp pretty badly after just a few weeks in direct sun, even though it was supposedly heavy-duty plastic.
I tried a mesh screen on mine last fall, thinking it'd help with leaves and stuff...but honestly, it clogged up pretty fast during storms. Ended up ditching it. Maybe a coarser mesh would work better without slowing things down too much?
Yeah, mesh screens can be tricky...I had similar issues last spring. What worked better for me was using a two-stage setup: first, a coarse mesh (like quarter-inch hardware cloth) to catch bigger debris, then underneath that a finer screen. The coarse mesh caught most leaves and sticks without clogging up too quickly, and the fine screen handled smaller stuff. Still gotta clean it occasionally, but way less hassle overall. Might be worth trying if your current setup isn't cutting it.