How to Clean Chemicals Out of Plastic Barrels

Correct ID prevents damage and bad reactions.

• Barrel type
• Tight-head (closed-top): two bungs; access with pumps or a spray wand.
• Open-head (removable-top): lever-lock or bolt ring; full opening for scrubbing.
• Residue type
• Water-based cleaners/detergents: usually respond to warm water + mild detergent.
• Oils/grease: use an alkaline degreaser; finish with a compatible rinse.
• Solvents/paints/adhesives: may need a specialty cleaner; test first.
• Acids/bases: neutralize carefully; never add water to acid.
• Mineral scale (hard water): may respond to mild acid descalers (see CLR/Lime-A-Way notes below).

This section gives a general process for known, non-reactive residues in HDPE barrels. Match the cleaner to the residue and SDS, and scale up only after a small test.

1) Empty and capture

• Drain as completely as possible.
• For viscous contents, drain as completely as possible, then manage any remaining residue according to the SDS and applicable waste rules.

2) Pre-rinse (warm)

• For known, non-reactive residues, add a small amount of water or cleaner recommended by the SDS. Gently move the liquid around inside the drum.
• Do not seal and roll a drum if you do not know what was in it, or if it held flammable liquids, strong acids/bases, oxidizers, or other dangerous chemicals.
• Drain into a labeled container.

3) Choose the wash method

• Water-based residues: warm water + dish soap or neutral detergent.
• Oils/grease: alkaline degreaser (pH ~10–12) per product directions.
• Adhesives/paints: warm alkaline wash + mechanical agitation; spot-treat with a compatible solvent only if the SDS allows.
• Acids/bases: only neutralize if you are trained to do it and the SDS allows it. Then wash the drum and dispose of the rinse water through an approved route.

4) Apply, agitate, contact time

• Tight-head: use a wand or rotary spray head through the 2″ bung.
• Open-head: scrub walls and bottom with a long-handle brush.
• Keep contact times short at first (5–10 minutes), then extend if needed.

5) Rinse thoroughly

• Rinse warm, then cool.
• Repeat until the rinse is clear and (if relevant) pH is neutral.

6) Optional: targeted second step

• For stubborn oils, use a compatible non-flammable cleaner or degreaser when possible. Only use solvent rinses if the SDS allows it and you have proper ventilation, ignition control, and a safe way to collect the rinse water.

7) Dry and inspect

• Invert on a rack or use filtered air (low heat).
• Check for cracks, bulges, brittle plastic, damaged rings/gaskets, and lingering odor. Replace worn bung caps and gaskets.

Short answer: sometimes, for mineral scale - but be careful.

• What they’re for: CLR and Lime-A-Way are acidic descalers designed to remove calcium, lime, and rust.
• On HDPE: Some acidic cleaners may be safe on HDPE for short contact, but check the product label or SDS first. Test a small spot, do not let it sit too long, and rinse thoroughly.
• Limits: These products won’t remove oils, solvents, or paint residues. They’re for hard-water scale, not heavy contamination.
• Never mix: Do not combine acidic descalers with bleach or ammonia.
• Rinse well: After any acidic product, rinse thoroughly and verify neutral pH.

If you want a barrel for water, raise the bar on cleanliness.

• Know the history: If the barrel ever held hazardous chemicals, do not use it for potable water.
• Prefer food-grade: Start with an FDA-approved food-grade water container with a known clean history. Do not use drums that previously held toxic chemicals, bleach, pesticides, or hazardous materials for drinking water.
• Use mild cleaners: Warm water + a mild, fragrance-free detergent. Avoid strong solvents.
• Sanitize last: Follow CDC guidance for bleach sanitizing. Use unscented household bleach diluted with clean water, let the solution touch all inside surfaces, pour it out, and let the container air-dry. Do not mix bleach with acids, vinegar, ammonia, or other cleaners.
• Final rinses: After sanitizing, pour out the bleach solution and let the empty container air-dry before filling. Only rinse after sanitizing if you are using clean, safe water and the guidance you are following says to rinse.

• Don’t mix cleaners (e.g., bleach + acid or bleach + ammonia).
• Don’t use abrasives that gouge HDPE.
• Don’t use barrels with structural damage (deep dents, cracks, brittle plastic).
• Don’t assume “food-grade” without documentation if the end use is potable water.

Cleaning used plastic barrels safely is about matching the cleaner to the residue, using a repeatable process, and respecting compatibility and safety rules. For drinking water, start with FDA-approved food-grade containers with a known clean history and follow CDC cleaning and sanitizing guidance. If residues are hazardous or stubborn, professional reconditioning is the safer choice.