What is the best water source for plants?
A natural water source will always be best, however most of us are not blessed with a stream at the bottom of our allotment. Rainwater collection systems are a cheap and easy way to provide natural water without chemicals. Alternatively if that is not an option then look at reverse osmosis filters. RO filters have become pretty cheap in recent years and while water flow is much slower, there is no reason you can't fill a container in advance.
Can I use tap water with your products?
Tap water contains one of two substances, chlorine or chloramine (a combination of ammonia and chlorine). Water companies are required to disinfect water supplies to ensure it is safe to drink and these chemicals are what they use to do it. Both are harmful to micro-organisms within the the soil, If tap water is all you have we recommend asking your water company which substance they use. If they use chlorine you can fill a barrel and leave the water for 24 hours allowing the chlorine to dissipate and you are good to go. Chloramine however can take much longer to disappear in which case we recommend a dechlorination treatment, usually just a couple of drops per litre of water.
Another method to dechlorinate is with a reverse osmosis filter. These can be connected to a hose and remove all impurities.