My beer seems to get funky infections quite a bit. What can I do to improve my sanitation?

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There is nothing more discouraging than working hard for a couple of weeks to brew up a beer, ferment it, keg/bottle it and then discover it has gone bad. One of the hardest things to do as a brewer is to dump all that hard work and time down the drain. Unfortunately, it happens occasionally even to the best of us. The best thing we can do is take it as a reminder that we can't get sloppy with sanitation.
Beer, wines, meads and ciders are all the result of the biological process of yeast fermentation. As such, conditions are deliberately created where stuff can grow. The world is full of microorganisms. Even just a tiny speck of live germs can ruin your batch. The whole trick to sanitation is making sure that yeast is the only thing that is growing. Here are some of the tricks that I use.

First of all, keep your stuff clean and store it that way. As soon as I empty out a fermenter, bottling bucket, racking cane or keg, I'll scrub it out real good, sterilize it and then store it that way.
The two most popular sanitizing agents are Chlorox bleach and iodophor. Both are effective at killing unwanted organisms. Iodophor is a bit easier to use, since it doesn't have to be rinsed after use. The active agent iodine can volatilize if articles are allowed to drip-dry. Make sure you don't get the liquid into your beer, though. Fowl-tasting phenolic compounds can develop as a result. If you are at all unsure, rinse out your stuff with a shot of cheap vodka. It is also a good sterilant, and trace residues won't affect the beer flavor.

Sterilizers are only effective if they touch all the material within your brewing equipment. They will have no effect if contaminated gunk keeps the surfaces from being rinsed. This brings up two important considerations:
1) All foreign debris must be scrubbed away prior to sterilization.
2) Sterilant must make it into the bottom of crevices and scratches.
Failures in sterilization can usually be traced to problems with one or the other of these principles.

Eliminating foreign debris often means using a bit of elbow grease. Old yeast cakes, mildew and dust need to be removed using a scrub brush if possible. For inside inaccessible surfaces, use a strong alkaline cleaner such as beer line cleaner to help loosen the stuff. Then blast it out with a fast jet of water.

Plastic can be a problem if it gets scratched. Most plastic surfaces are fairly hydrophobic, so sterilant won't penetrate to the bottom. The more scratched up a bucket it, the longer it needs to soak to become clean. Since plastic is cheap, many brewers choose to just replace it after a year or so of brewing.

Kegs are full of crevices. For best results, disassemble all of the parts and soak them individually in sterilant. Don't just give the assembled keg a flush. Also, when you finish off a keg, leave it under CO2 pressure until you have a chance to clean it out. Many organisms require air to grow.

Watch out for airborne contamination. Air is full of pollen, molds and bacteria. If possible, brew indoors and close the window. Keep your pots, carboys and bottling buckets covered as much as possible. If you serve kegged beer, watch out for contamination in the gas lines, especially if beer has backed up into the lines. Finally, remember that even with the best possible sanitation, some number of adverse organisms will always get into the beer. For this reason, you want to make sure you have a big active starter going when you pitch your beer. An active yeast culture will impede bacteria growth, and will win the competition for sugars, nutrients and dissolved oxygen. Also, the alcohol level will rise faster, which will kill off many organisms.

Hopefully these tips will help you make consistently clean beer. Clean beers score better in competition, they keep better, and most importantly, they taste better.