Wine Faults - Common faults you may encounter with wine.

The wine maker spends at least a year, sometimes several years, bringing you a delicious, lovingly made wine that will delight you for years to come. After carefully laying it down in your cellar or cupboard under the stairs, you bring it out for that special occasion when your wine loving friends visit for dinner. Unfortunately, on pouring the wine, you are horrified when you take your first gentle sniff! It smells horrible!! That’s definitely not how the winemaker intended it to be…

wine fault explosion

So what can go wrong with wine, and how do you know if it’s faulty??

Wine faults can be detected by looking at the wine, smelling the wine and tasting the wine. Some are more common than others, but if you drink enough wine, eventually you will likely encounter some or all of these:

Cork taint (TCA):

What is it? This is a taint caused by a compound present in the natural cork (2,4,6 Trichloroanisole if you must know!). It is created during the manufacturing process of the cork and can work its way into the bottle. It is present in around 2-3 in every 100 bottles you open.

How can you detect it? It smells like a damp dishcloth or wet cardboard. It’s a bit dank and musty and can result in a loss of fruit on the palate too.

What can you do about it? Nothing really! It’s the second most common fault and there isn’t an easy remedy, except send it back! Screwcaps overcome this problem of course.


What is it? This happens when too much air gets into the wine, either during the making of the wine or during storage. If you slice an apple and leave it to one side, it turns brown quite quickly. This is a form of oxidation.

How can you detect it? In a white wine, it will turn the wine brown over a long period of time. In a red wine it eventually loses its colour. A sniff will quickly confirm if it’s oxidation; it will smell ‘sherried’ or ‘maderised’, lacking freshness and fruitiness. In the mouth it can taste of green apple, walnut or fennel.

What can you do about it? Very little as it happens. You could use it to make a decent gravy…

wine fault oxidisation

Microbial and bacterial taint:

What is it? Sometimes, microbes other than yeast can reside in wine. The most common one is Brettanomyces or ‘Brett’ as winemakers term it. It produces several compounds that can alter both smell and taste. It often resides in wine barrels and is generally the result of poor hygiene in the winery. Oaked reds low in acidity are particularly prone to Brett.

How can you detect it? It tends to smell like sweaty saddles, farmyard or perhaps even medicinal. At low levels, it can be seen as adding a certain complexity to a wines aroma. At high levels, it’s off-putting to say the least!

What can you do about it? Nothing much. Once it’s there, that’s it. Over time it can get even worse!

Volatile Acidity

What is it? It is caused by a combination of too much air, heat and bacteria during the winemaking process.  The bacteria can be a rogue yeast which creates acetic acid, the acid that gives vinegar its particular smell and flavour. In low levels, like Brett, it can be seen as a good thing. At high levels it is just plain unpleasant.

How can you detect it? It gives off a distinct vinegary or balsamic smell that at high levels can be distracting. It used to be very prominent in Italian red wines (and still is in some cases).

What can you do about it? Nothing, although at low levels, it can add complexity to the aromas.

wine fault volatile acidity


What is it? Damage caused by excessive exposure to UV light. The UV light transforms the amino acids in the wine into stinky compounds such as dimethyl disulphide. A wine in a clear bottle stored by a window would be a likely candidate for this fault. The fault can happen very quickly.

How can you detect it? It mostly affects wines in a clear bottle and especially ‘delicate’ wines such as rose, pinot grigio and sparkling wines. A wine affected by Lightstrike can taste and smell of cabbage or ‘wet dog’.

What can you do about it? Nothing once it has occurred. To prevent it, keep your wines out of sunlight. Wines stored in restaurants and supermarkets can be especially affected.


What is it? This can happen if a wine is made without introducing enough oxygen in the winemaking process. Wine that are fermented and aged in inert stainless steel can be most susceptible. Yeasts need a little oxygen during fermentation. If they don’t get enough, then they can create bad-smelling compounds. This fault can be more prevalent in screwcapped wines.

How can you detect it? A ‘reduced’ wine often smells of rotten eggs, cabbage or rubber.

What can you do about it? You can eliminate the bad egg smell by opening the wine well before serving and aerating it (double decanting). That is, pour the wine from bottle into a clean container such as a jug, then pour back into the bottle (making sure you clean it first to remove any possible deposits).

wine fault bad smell


What is it? Essentially it’s a bacteria which can occur in the vineyard or winery. Grapes that have been affected by grey rot or dirty barrels can cause this fault to occur. Interestingly, it is the same bacteria as ‘Petrichor’ that is, the smell of rain on impact with the ground.

How can you detect it? The wine smells musty or a bit earthy like beetroot, turnip or freshly tilled earth.

What can you do about it? The winemaker can eliminate Geosmin by greater care in selecting the grapes during harvest. They can also use filtering methods which strip out the taste and smell. However, for we wine drinkers, there is little that can be done other than decanting and hoping it will disappear. But there’s no guarantee.

wine fault dirty barrel


When a ‘fault’ isn’t a fault!

Often I get asked about a number of common faults with wine which turn out not to be a fault after all. Here are a few common ones:

‘Corked’ wine:

Yes, it still happens! Pieces of cork floating on the surface of the wine usually indicates your corkscrew has worn out and you need another! It does not mean that the wine is corked. See above (cork taint). Simply fish out the pieces with a spoon or nearby implement and enjoy the wine…

Pieces of ‘glass’ in my white wine:

In some white wines you might detect at the bottom of the bottle a deposit that look like pieces of glass. They are in fact tartrate crystals and can form as a deposit when a wine has been cold stabilised. Winemakers do this to remove excessive potassium bitartrate (or cream of tartar) from their wines. These are naturally present in grapes. It is in fact a good sign, as it shows that the wine is natural and has not been excessively filtered. They will not harm you, but are best left at the bottom of the bottle, or decantered out before serving.

Sediment in my red wine:

Red wines can often throw a sediment, especially red wines with lots of body and colour. It can occur over a period of ageing when a process of polymerisation occurs. That is, the polymers in the wine combine with tannin and other compounds in the wine and drop out over time to form sediment. There are over 1,000 compounds found in wine and these in part add complexity of flavour, colour and texture in your wine.  It can take place over a ten year period or more and only really applies to wines made for long ageing/cellaring.

A sediment or deposit in your wine is a sign that the wine has not been over filtered and over-processed; a good thing. But you will need to decant the wine first so you don’t end up with a cloudy wine full of solids!