I live in a hard water area and have just constructed my polytunnel. I will irrigate with rain water as often as possible, but it is inevitable that I will need to use our fresh water supply regularly. I am concerned about the consequences repeated use of hard water will have on the chemistry of my soil. Any advice would be really appreciated.
However, the amount of lime delivered by the water when watering is negligable and of no concern. Just do not use it on plants that are lime-haters, such as azaleas and citrus.