BIAB Small Filter Bag with Drawstring

BIAB / Fruit Straining Filter Bag

This small filter bag by Dark Rock Brewing is designed to fit containers up to 22?cm in diameter and 18?cm deep.

Ideal for one-gallon batch brewing, fruit straining, or small?scale BIAB setups.

The drawstring closure makes it easy to secure around the container lip and lift the bag for draining and clean up.

It’s a reusable, food-grade mesh designed to hold mash grains or fruit pulp effectively.

Bag Specifications

• Max container width: ~22?cm
• Depth: ~18?cm
• Material: Food-grade, fine mesh (polyester or similar)
• Closure: Drawstring with locking mechanism
• Applications: BIAB, fruit straining, small-volume brews

Usage Tips

Secure the drawstring around the container lip so the bag doesn’t shift during sparging or stirring.

After mashing or steeping, lift the bag and let it drip before squeezing gently to recover wort.

Rinse the bag immediately after use to avoid sugar or grain residue drying in; air dry fully before storage to prevent mould or odour retention.

Suitable Brewing Scenarios

• 1?gallon / 5?L BIAB batches: Perfect size for small homebrew setups
• Fruit wine / fermenter straining: Capture pulp cleanly during transfers
• Small extract or partial mash kits: Use as a filter for adjuncts or small-grain additions
• Prototype / recipe development: Use in test batches before scaling up

Why Use This Bag?

Compared to regular grain bags or mesh filters, this size gives more control in small batches.

The drawstring allows for easier handling and drainage, reducing mess and grain loss.

Brewer’s Tip

If you’re doing manual lifts, route the drawstring over a hook or rod to guide the bag straight up and avoid stress on the seams.

Use gentle squeezing—not twisting—to extract extra wort.

For cleaning, boil the empty bag (without yeast) in soda ash solution or PBW for sanitisation, then rinse thoroughly.

It will last many brew days if treated well.