Rainwater, with its simple chemistry, makes it easy to grow plants. This is especially helpful if you are new to growing. Unfortunately, droughts happen. Here are some tips to help you through the dry times.
Catchment Planning – try plan the best you can for what you think your water needs will be.
Mixing with Regular Tap Water – this is a great way to stretch your water in dry times. Mix half rainwater with half tap water. This will most likely raise your total dissolved solids (TDS), so be sure to account for the extra dissolved solids when you use a TDS meter. Mixing with tap water can also change the pH of the water. A good rule of thumb is: If it is deemed safe to drink you should not have any problems when using it to mix. Another good rule of thumb is when the TDS of your water gets to around 2000ppm it may start becoming unsuitable to grow plants with. If the water you are mixing with is high in sodium or boron, damage to plants may start sooner.
Reverse Osmosis(RO) Water – reverse osmosis produces water similar to that of rainwater.