Our cold water is totaly fine for drinking - and for babies over 6 months, it's cooled boiled water before that. All the UK mains water is very clean, but does taste different around the country and we have hard and soft water areas. My bottles always feel "scummy" after a visit to the in-laws as they live in an area that has hard water so they have to descale everything that heats water quite frequently.
The heating water to 70 degrees is fairly recent, it's to make sure any bacteria is killed in the powder.
Kaynay - The water needs be a lot hotter than room temp - a kettle bolied and left for about 15 - 30 mins is around 70 degrees.
I'm not sure what the statistics are on babies made ill through bacteria in powder. It's probably not that high really, and the risk you take making feeds before hand is down to your comfort levels with all the info to hand. My two have been on reflux formula which has to be made with cold water and both have been fine. I did however notice that the recent tins now have a comment that if you are using this formula with a preemie/ very small baby to get advice for making it up - probably to cover themselves because of the 70 degree thing.
Just something else to make you feel guilty for the choices you make
Laura