How long does an opened keg keep and how do you store it?

Three things determine it: the temperature, the amount of oxygen that gets into the beer and whether the keg stays under pressure.

Warm beer loses flavour faster than cold beer. Oxygen gives an old, cardboard-like note. And if the pressure drops, the carbon dioxide escapes and flat beer remains. A keg that stands cold, stays connected to carbon dioxide and is not constantly lugged around therefore lasts much longer than a keg that ends up in the shed after the party.

Leave the keg connected, keep it cold and place it in a fixed, quiet spot so the beer is not shaken up all the time.

The Brewers Association recommends a temperature of about 1 to 3 degrees for a draught system. If you cannot achieve that at home, keep the keg as cool as possible and out of the sun in any case. Do not disconnect the keg to move it, because every time you disconnect it, air gets in. Then tap the beer within a few days.

A hand pump pushes ordinary air into the keg, and the oxygen in it attacks the beer.

With a carbon dioxide installation no oxygen gets in, because the gas that displaces the beer is already in the beer. With air that is different. The Protocol Kelderbierinstallaties of Nederlandse Brouwers describes cellar beer tanks with a flexible inner wall, where compressed air presses from outside against the bag and does not touch the beer itself. Precisely that separation principle is missing with a simple hand pump on a party keg.

Draw off the remainder into clean, tightly closing bottles and chill them right away, because beer deteriorates fastest in a half-empty keg without pressure.

Fill the bottles to the top, so that as little air as possible remains above the beer, and close them straight away. Drink this beer first and do not put it among the rest in the cupboard. If a lot really is left over, it is still perfectly usable in the kitchen, for example in a stew or in batter.

Clean the beer lines every two weeks, because the Brewers Association names that as the standard frequency for a draught system.

In a line that is not cleaned, yeast and beer residues remain behind, and they give the next keg a sour or musty aftertaste. After a party, flush the line and the tap with clean water and do not leave anything wet and closed. For fixed cellar beer installations, the Protocol Kelderbierinstallaties of Nederlandse Brouwers also applies, with an inspection every six years and a working pressure of at most 3.0 bar.