This is a test of commonsense. Complete the next sentence:

How to brew gaiwan tea
Choose the best water.
Ninety nine percent of tea is water, so it's important to give some thought to the water you use for brewing. Tap water should be avoided since its chemical treatment imparts undesirable flavors and odors which interfere with the delicate aromatics of tea.
Home filters and other water purification systems can minimize and, in some cases, eliminate these problems. The best water for tea brewing is spring water with a natural mineral content that's neither too hard nor too soft.