Cleaning and sanitising are two different jobs

Nearly every infected batch traces back to one misunderstanding: treating cleaning and sanitising as the same step. They are sequential jobs with different chemicals, and skipping either one costs you beer.

The distinction

Cleaning removes visible soil — protein, hop residue, yeast, beer stone. It is a physical and chemical process, and it does not kill anything in particular.

Sanitising reduces microorganisms to a level that will not spoil beer. It does not remove soil, and — critically — it cannot work through soil. Organic matter shields microbes and neutralises sanitiser on contact.

Sanitiser on a dirty fermenter is theatre. Clean first, every time.

Cleaning: percarbonate

Sodium percarbonate is the standard brewery cleaner — sold as PBW and various house brands. In water it releases hydrogen peroxide and soda ash, which lifts organic soil off surfaces without scrubbing.

Use it warm, around 40–50 °C, and give it time. A fermenter with a stubborn krausen ring soaked overnight will wipe clean with a cloth. That is the point — you should not have to scrub.

Rinse thoroughly afterwards. Percarbonate is alkaline and will neutralise an acid sanitiser if left behind.

Avoid household dish detergent. It leaves a film that destroys head retention, and the perfumes can carry into beer.

Sanitising: no-rinse acid

The standard is a phosphoric acid blend — Star San and equivalents. Diluted correctly it sanitises in 30 to 60 seconds of contact and needs no rinsing.

Two things people get wrong:

• The foam is fine. "Don't fear the foam" is genuinely true — it is surfactant, it is food-safe at use dilution, and it will not affect your beer. Draining the foam out wastes effort.
• Surfaces must be wet. Contact time means wet contact time. Spraying and immediately tipping out does not sanitise anything.

Mixed sanitiser stays effective for a week or two in a sealed container if made with distilled or low-alkalinity water. It has gone off when it turns cloudy or its pH rises above about 3.5.

What not to scrub

Never use an abrasive pad or a scourer on plastic. Every scratch is a channel that harbours bacteria and shields them from sanitiser. A scratched plastic fermenter is a permanent infection risk and should be replaced, not rescued.

Soft cloths and soaking only. This is exactly why percarbonate matters — it makes scrubbing unnecessary.

Stainless tolerates more, but avoid steel wool, which leaves iron particles that rust and pit the surface.

The three places infections start

In our experience, almost always one of these:

1. The tap. Fermenter taps have internal surfaces that never see a cloth and hold beer residue between batches. Disassemble it completely — every brew, not occasionally. This is the single most common infection source in home brewing.

2. Gaskets, O-rings and lid seals. Beer wicks under seals and sits there. Remove every O-ring, clean under it, and inspect for perishing. They are cheap; replace them annually.

3. Transfer tubing. Vinyl tubing goes cloudy and micro-crazed with age, and you cannot clean the inside of a three-metre tube properly. Tubing is consumable. Replace it every six to twelve months rather than trying to save it.

A workable routine

• Rinse everything with hot water immediately after use, before residue dries. This is the highest-value thirty seconds in the whole process.
• Soak in warm percarbonate. Overnight for anything stubborn.
• Rinse well.
• Sanitise with acid sanitiser, 60 seconds wet contact, no rinse.
• Assemble wet and use immediately.

Everything that touches beer after the boil needs this. Before the boil, it does not matter much — the boil handles it. After the boil, it is the only thing standing between your beer and everything else that would like to eat it.