Water make up a big part of your tea. Many of us are willing to spend considerable amount of $$ on our tea. For many tea drinkers, we may spent a few dollars for 10g of tea leaves for a session of tea. I have yet to read on tea forums or blogs about the cost of water in a tea session.
I suppose water is considered cheap. If you are lucky (like me), the tap water in your country may be drunk 'straight from the tap' and I would be using this tap water to boil and make tea. In countries where tap water is not directly drinkable, one would consider maybe adding a filter to 'clean' the tap water or may use bottled water in the home.
My friends in China, Hong Kong and Malaysia had told me to drink bottled water whenever I travelled to visit them. I noticed, in all these 3 places, that my friends used quite 'high tech' electronic water filtration devices in their homes to filter their tap water. The tap water is ran though 4-5 filtration modules before it is 'considered safe to drink'. The filters, I was told are changed 2-4 times a year.
When it comes to tea, my friends and teashops in these 3 countries would used bottled water for their tea sessions. There are many brands of water available but in Malaysia, the 'Spritzer' brand is preferred and in China. the 'Nongfu' brand is used for tea brewing. I am sure these folks have tried many brands before settling on these preferred brands. If my math serve me right, it cost about US$1.50 to buy about 2 litres of water in these 2 countries. So if you use 2 litres of water in a tea session, than the water cost is US$1.50 in this example.
It was surprising, or not surprising, that I found the water from these 2 brands tasted quite similar to each other. When I brewed ripe pu erh tea at home using these 2 brands, the water tasted a tiny bit sweeter than my home tap water. It was a fun experiment to do and I urge my readers to try the occasional bottled water in your shops to see whether you can discern any difference in your tea.
I also encourage that you use 100c (boiling water) when you brew your tea....it does make a difference. Do also remember to use boiling water as well for subsequent infusions as well.
I also know a few of my hardcore tea buddies (3 of them) would go outdoors to collect spring water and bring home to brew tea. They tell me its the best water.
We should be thankful we have water to drink. I have read articles that there will be future wars among countries whose conflict will be over water.