[Anton]

This morning I went to pick up two 220-litre second-hand plastic water barrels to catch rainwater in my vegetable garden. The fellow who was selling them told us they had previously contained solvents.
The garden has several other water barrels (three of us are sharing the garden) and they were there before any of us arrived, so we have no idea what they used to contain. I am wondering if it is safe to use water barrels that used to contain solvents to capture rainwater!
Advice please.

Anton

[Aunt Sally]

What colour are the barrels ?

Did they say what the solvent was ? 

Is there a label on the barrel ?

[Subversive_plot]

Anton:

 My job involves regulation of cleanup of hazardous waste sites, so I am familiar with many types of chemicals from that perspective.  "Solvents" can cover a lot of materials. I wouldn't be too worried about acetone or ethanol, for example, but I would be more concerned about other solvents, such as tetrachloroethene. Are there identifying marks on the barrels, with numeric codes (such CAS number), names, hazard warning labels, or transportation safety information related to the former contents?  If yes, photograph them, I may be able to help you figure out what was in the barrel.

I wouldn't go sticking my nose in a barrel that formerly held an unidentified solvent, but if you detect a solvent odor when the barrel is open, it may not be completely decontaminated.

Many solvents are volatile, some could potentially evaporate if given enough time exposed to open air.  Others (especially petroleum solvents) may be tougher to get rid of.

[Anton]

Thanks for getting back to me.
The barrels are blue. No markings. He didn't say what the solvent was. There is a bit of smell. tetrachloroethene smells a bit like pears, doesn't it? It's not that smell. He said he normally sells the barrels for people exporting goods to Africa so the items are not damaged in transit!

Anton

[Anton]

Would they be dangerous for the garden?

[Aunt Sally]

I think blue barrels are food grade,  I’ll check that out.

[Aunt Sally]

Yes, they are food grade but it would be nice to know what has been in them.

https://www.bluebarrelsystems.com/blog/history-blue-plastic-barrel/#:~:text=Blue%20is%20the%20standard%20food,for%20reuse%20or%20%22upcycling.%22

[Subversive_plot]

Assuming the container looks fairly clean and does not have any gross level of contamination (oily or other liquid residues), and you can open it up to clean the inside, it can be decontaminated. 

Even a container that has some residue can be cleaned if the residue is not strongly greasy or tarry.  Requires an extra step.

Here is how.

Extra Step: wipe the interior with an absorbent material (kitchen roll or similar) to remove as much residue as you can.  Discard that soiled kitchen roll in the trash. Apply a liquid detergent, somewhat heavily (washing up liquid is fine).  Scrub, rinse Important: plan any decontamination to occur in a place where you can discard wash or rinse water into a drain connecting to a sanitary sewer, don't discard on the ground. The wastewater treatment process can treat low levels of most contaminants.  Make sure you are not running afoul of any UK or local laws!

1. If you just have a little lingering odor, or you completed the extra step above, clean again with washing up liquid and warm water, scrub thoroughly. (remember . . . sanitary sewer for water disposal).

2. Potable water rinse 3 times, (sanitary sewer disposal).

3. Rinse the inside with an inexpensive solvent, such as rubbing alcohol. A hand sprayer is good for this, huge quantities are not needed, a small amount will do.  Drain the alcohol into some absorbent material (like paper), allow to evaporate.  Discard paper in trash when dry.  Allow the barrel to air dry.

This is very loosely based on US Environmental Protection Agency methods for decontaminating field equipment for use in collecting environmental samples.  It should get your barrel clean enough to use to store water for the garden.

[Anton]

Thanks a million for the decontamination advice and putting my mind at rest. I was starting to feel a bit depressed being lumbered with two unusable barrels.

The barrels looks perfectly clean and have been rinsed out, according to the seller.  There is a lingering odour but that is probably because they were covered with a fairly hermetic-looking top, that has a metal hoop around the top to lock it closed. I have left them open in the vegetable garden, and hopefully the smell will dissipate and as it is now pouring with rain it, the containers will get another rinsing.

The owner of the house adjacent to the garden has a pipe leading from his roof to a metal drum in my patch (he used to work in the garden once upon a time). When I started in the garden last year, I discovered the metal container has holes so no longer held the rain. So I am going to get rid of the drum (the owner has given me his permission) and replace this with a plastic one and hopefully hook up the other barrels.

[Subversive_plot]

tetrachloroethene smells a bit like pears, doesn't it?

Anton

FWIW, I wouldn't compare the odor to pears. 

I'm old enough that I recall having a childhood surgery where the anesthetic was ether (back in the medical dark ages!!).  The odor of the ether, and my 5-year old self fighting against medical staff as it was applied, is the only thing I recall from the surgery. The odor of tetrachloroethene (also called perchloroethene or PCE) is comparable to that ether odor.

PCE is a solvent that has been used in dry cleaning. If PCE was used for dry cleaning where you live, you may have smelled it at a dry cleaning operation.

[Anton]

Thanks for your post Subversive Plot.
I used to be a student nurse back in the mists of time so I can remember the smell of ether. I don't think the barrel whiffs like ether. A bit sickly sweet. Anyhow, it's been raining like made for the last few days so hopefully this will get rid of the smell.