Why is my beer hazy, or even muddy looking?

So, you've probably read my post on sediment in beer, but if not, that's okay.

Every once in a while, the sediment or haze gets extreme, or, if you've had the beer before, unusual even for the particular beer you're drinking.

This is usually the case in draft beers which are unfiltered or undergo secondary fermentation in the keg, and there's a few reasons this happens.

First of all, it is perfectly natural, and perfectly normal, and not a sign of a flaw in the beer, and definitely not that the beer is unsafe to drink.

As the post above discusses, sediment or haze is usually caused by the dead yeast cells remaining in an unfiltered or bottle/keg conditioned beer.  This is why unfiltered beers, such as hefeweizens, wit beirs, and various Belgian beers are usually hazy and opaque.

On the other hand, sometimes the haze goes beyond opacity to actually make the beer darker, or almost muddy in appearance.  While in hefeweizens, these beers usually pour within the normal color range for the style, and unless you are familiar with the particular beer you're drinking, you might not even notice, it can be particularly alarming in Belgian wit beers, golden ales, tripels, etc.

The reason this happens is fairly simple.  Dead yeast cells are heavier than water and the other things that make up the majority of your beer.  If a keg of beer sits stationary for a while, the yeast will start to make its way toward the bottom of the keg and become concentrated there, causing a darker, more murky appearance.

The way kegs work is that the beer being pulled from the tap is actually coming through the stem of the barrel from the bottom of the keg.  This means that, depending on how long a beer has been sitting in a color, and how it was stored, the beer can be darker at either the beginning or the end of a keg.

If a keg has just been tapped, and is pouring with a muddy color, it is likely a sign that the beer has been in the bar's cooler for a while, and has been stored upright.  Luckily for us, most unfiltered beer styles are not harmed, and may actually get better, from aging.  On the other hand, if the keg gets darker toward the end, it is usually a sign that the beer has been on tap for a while, or was stored upside down before being tapped.  In fact, many brewers recommend that their unfiltered beers either be stored upside down, or are agitated just before serving.  The reason is that this way, the yeast is concentrated at the top of the keg.  If the keg is on tap for a reasonable amount of time (a few weeks), the yeast will slowly settle, and the beer shouldn't pour "muddy" at all.  On the other hand, if the beer is particularly popular, and moves quickly, the yeast concentrated at the top of the keg won't have time to settle/spread throughout the keg, and when the end of the keg is reached, the beer which was formerly at the top of the keg will have a high concentration of sediment, and will pour with a murky/muddy appearance.

As mentioned in my sediment post, I have heard (from very unscientific sources, of course), that the dead yeast cells are actually very nutritious.  In most draft beers, they may affect the mouth feel of the beer, but honestly, if you were to blind taste the "bottom of the barrel" against a glass from the middle of the keg, you wouldn't know the difference.

So don't let the dirty/muddy appearance of that beer scare you.  Enjoy it!