Originally Posted by Robms88
I used my tap water and it is quite hard water. Yes, I am doing extract kits. I guess the only thing I can do is to experiment with different yeasts, use bottled water that is not hard and use lower temperatures in order to find the cause of the problem.
Yes, the best bet is to do everything possible to give your beer the best chance of success. Since you specifically said it has a bitter aftertaste, my bet is still on the water. However, I'd still go with one of the other yeasts, and better temp control will absolutely produce a better beer.
Are you able to get a water report from your water company? If so, you can compare your water profile with the typical water profile for the style. Beers typically brewed in regions with hard water (Stout for example), will taste better with hard water. Beers brewed in regions with soft water (Pilsners) will taste better with soft water. If you brew a pilsner or amber ale with hard water, it will taste bitter. If you have your water's profile, you can blend it with bottled water to achieve a more appropriate amount of mineral content. That said, you could get away with just using bottled water and not worrying about blending.
Since your kitchen stays at about 20*C/68*F you'll probably want to bring your fermentation down a few degrees depending on the yeast strain. You could probably manage this easy enough with the swamp cooler method. This basically entails putting your fermentor in a tub with some shallow water, draping a cloth over it which hangs into the water, and blowing on it with a fan.
My last question for you is "How long do you let your beer ferment and bottle condition before drinking it?" Could it also be that your beer is just green?