Filtering rain water - here's an instructable I did on making a rain water filter which is self cleaning, has no moving parts and has been running in our garden for years without maintenance.
The water is clean enough to supply toilets, run the washing machine and irrigate the garden.
I ran a system for making spring water drinkable, but that required a 5 micron filter which only lasts a few months and a UV light system to sterilise it- which was expensive and used too much power, so I abandoned that.
Tim's provided all you need to know on pH I'm pretty sure.
Now you have a filtering option.
The internet, eh?
