Tap water may sometimes contain too much calcium, and therefore be too alkaline, for watering plants such as orchids or cacti.
It is very easy to remedy: mix 1 teaspoon (= 5 ml) of white vinegar (8 %) with 1 gallon of water (5 l).
The exact proportions are 1 ml vinegar per liter of water.
If you are unsure whether your water is too alkaline or not, you can test it with a pH test or litmus paper.
- Tap Water: Thegreenj