Just like sunlight, water is essential for plants to live. You can’t have too much, and you can’t have too little.
What needs to be understood about watering plants, is this: Not all water will work for all types of plants. I’ll explain.
In a general sense, most plants will take whatever water that’s available. Certain plants however, will not last very long, when consuming certain types of water.
Many plants are okay with taking tap water, but as most of us know, tap water is filled with chemicals. Most of it is unacceptable for plants in general. You have chemicals like fluoride and chlorine, neither or which is good for plants. Just imagine, if it’s not very good to put on your plants, then you understand why it’s not good to drink.
When looking at certain plants, plants that prefer chemical and mineral free water, which is basically distilled, rain, or reverse osmosis water, you can look at the carnivorous plants, where they get their needed nutrients through capturing their prey, and absorbing nutrients from their food. Their food being primarily insects. Water with minerals, will be a problem for those plants, because they would prefer not to have them. It can tolerate some nutrients in water, but again, they would prefer not to have them in their water.
Tap water isn’t all that bad for carnivorous plants, as long as it’s parts per million is quite low. Anything from 50 PPM to 140 PPM, is much closer to ideal for carnivorous plants. Having a TDS (Total disolved solids) meter to measure what’s in your water, is essential for your plants water, and your own drinking water.
Spring water may have minerals in them, and generally the TDS readings are in a similar range to tap water, at their lowest readings. I’ve tested some I purchased from my local supermarket, and they measured around 30 PPM, from what I had at the time. Would I use spring water to water my plants? Maybe, but I would refrain from using that on carnivorous plants.
Distilled water would be seen as the best, for pretty much all plants, because there’s just water and no chemicals and no minerals in it. TDS meters will generally read 0 PPM for distilled water. It’s best in my opinion, because no plants will absorb anything other than water. Should anything else be absorbed, that will come from the media the plants are already in.
From what I’ve dealt with when it comes to water, watering and spraying, generally isn’t an issue, especially with the tap water I have available to me. The measured TDS readings go from as low as 50 PPM and as high as 60 PPM, depending on the temperature (I’m not sure why this is, but this is what I’ve observed).
What’s good about watering plants, is that depending on how many plants you have, the more you water, the likelihood of raising the humidity around it will occur. This can occur best when misting or spraying your plants. I’ve seen this firsthand, with humidity gauges nearby to notice the differences. I’ve seen some areas, where the humidity rose from as little as 5%, to as much as 15%. If you have bushy plants, that will be more of an incentive for the humidity to be increased in that area. That increase will also be beneficial towards plants that thrive in tropical climates; albeit minimal, since it’s unlikely it will go nearest to high percentages like 80% or 90%. Stranger things have happened.
I do have a tank that will help some plants, mostly those deemed tropical plants, to have that increase in humidity, to where they can reach as high as 90%; as long as the tank is covered, this will be the result after a good, strong misting.
So yes, water and the types of water used for plants does matter. Your safest bet, if you can capture it, rain water. However, for convenience, have distilled water. There are two ways to get distilled water. Either make it yourself, with a water distiller, or purchase it from the local supermarket. I don’t know much about reverse osmosis water just yet, but when I do, I’ll document what I observe. Tap water is still okay, as long as it measures with the readings mentioned previously. No higher than 150 PPM, but best to be as low or lower that 50 PPM.