Yes - before deciding on which system to use to get your water treated, you should get it tested. Don't just check for tannins, as wells commonly contain bacteria and sulfur, too, which give water an unpleasant aftertaste, may affect water flow, and may even make water unsafe to drink. If your water isn't clear, it may contain iron. Once you know what you need to remove, it'll be easier to buy the right systems for the job.