17 May 2021

What the ‘taint’ is that?

What the taint is that?

Part 1

The long-awaited re-opening date for the remainder of our great British pubs is here at long last. We know it’s already a flurry of activity out there as you get your cellars and bars stocked and ready to go, but are you sure your dispense system is problem-free? To help you spot problems before you start to serve, we bring you our troubleshooting series on common beer taints.


Have you ever discovered one of your beers tastes a bit ‘soapy’ – just as you were about to open? Or had a customer return a pint telling you, “It tastes like cardboard”? How about someone complaining their beer “tastes like it’s been poured through a musty old Bible”?!

All of these odd-sounding descriptions are things people have actually said about tasting tainted beer. Read on to find out what’s behind these taints and, more importantly, how you can avoid leaving your customers with a nasty taste in their mouth and your pub in the dog house.

What do we mean by taints?

A taint is another way of talking about an off-flavour in beer. They are most often caused by spoilage bacteria or undesirable chemical reactions. Occasionally, contamination can happen during the brewing or kegging process, but the greatest number of taints happen after beer has left the brewery and once it is being dispensed.

You’ll notice that each of our posts includes some seemingly quirky and unusual descriptions. Through our work on taints, we’ve found that language can be a barrier to diagnosing – and solving – the problem. By building a vocabulary of taints, or a list of the weird and wonderful things that off-flavours remind people of, we hope we can help you spot and solve these problems much more quickly.

In this series we’ll look at four different taints, starting with:

No. 1: Trichloroanisole (TCA) “Tri-chloro-anisole.”

Commonly found in beer lines that have been out of use for a while, trichloroanisole causes a ‘water taint’. It’s abbreviated to TCA, which is less of a mouthful – and believe us, nobody wants a mouthful of this. Once tasted, never forgotten.

How to detect it:

Very little TCA needs to be in the lines for it to be detectable. Its taste and smell are reminiscent of old, musty buildings, such as churches, where damp and mould are a problem.

Drinkers might say:

“It’s as if my beer’s been poured through an old Bible.”; “It reminds me of an old paddling pool.” Or “It smells like an antiques shop.”

What causes it:

The main cause of TCA seems to be when dirty lines are left in chlorinated water. Then, even once cleaned and blown to air, the problem is still reported. This goes to show that all that’s needed to generate the taint is a little water and a bit of organic contamination from waste beer. It’s an easy, but costly, mistake. Soggy pythons caused by leaks and broken insulation are also thought to be a contributor to water taints, as this is where the TCA can leach into lines.


NEVER leave your lines in water! Always ensure pythons are well maintained. Beware that once you have a TCA taint it’s VERY difficult to get rid of it – and you only need a tiny amount for it to be detectable in beer. If you’re faced with this taint you have two options, either replace the lines or commission an Avani SOS L3 taint removal procedure.

Look out for our next post on Dichlorophenol (TCP), which is believed to be a precursor to TCA.

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