Carrots are a staple for many people around the world.  They work well in stews, in salads and provide a very high source of nutrients and minerals.

My carrots taste bitter, what's wrong?   I am watering for 20 to 30 minutes using a drip system 3 times per week.  I use the Mittleider organic method of growing, and grow in containers, or Grow-Boxes.

Your problem is a lack of water.  You should always water daily until you see water coming out the bottom of the container or box.  Hoses which soak on a ongoing basis seldom do the job.

If you were growing in the soil, water still would most likely be the culprit, although if you are not feeding accurately and make sure you do so for five weeks.  It is possible you still have a nutrient deficiency.  Be sure you are using the Foundations  natural mineral nutrients as fertilizers. 

I recommend you automate your watering using the PVC pipe system taught and demonstrated in the Mittleider gardening books.  This system is inexpensive to build, it waters very accurately, and will last practically forever, if you take care of it.