Is Tap or Rain Water Better for Plants?
Plants require water to germinate, grow and blossom into full-fledged healthy organisms. Water provides them with minerals as well. At least rainwater does. But rainwater cannot be available all year round. Tap water, on the other hand, may just provide the wrong ions to the plants. So it is very important to carefully weigh both options before deciding which one is the best for your plants.
Rainwater is naturally available and thus is an easy way of watering plants. Moreover, rainwater has a lot of dissolved nitrogen in it. Nitrogen is a very important mineral for plants because it is involved in many physiological processes within the plant. Nitrogen gets into rain droplets in the atmosphere, every time lightning sears through the air and water vapors. Lightning brings about a reaction of nitrogen with water, resulting in a weak acid. This is very important for plants because they cannot take nitrogen from air but depend on the soil.
Rainwater’s Down Side
Recent increases in air pollutants and greenhouse gases can be attributed to acid rain. Acid rain has a low pH level, which is harmful to plants. Most plants cannot withstand such a change in the pH level of the water. Also, you can never solely depend on rainwater to maintain a healthy growth of your plants, since for that you would have to collect rainwater and harvest it for perennial use. That would be impractical.
Tap Water Impurities
Some gardeners say tap water is good because it is purified for use at home. According to advocates of tap water, if we can drink it, it should be safe for plants as well. The truth is that tap water undergoes chemical treatment, which reduces its pH levels and also increases the sodium and chlorine concentration. The high levels of these ions are harmful to plants because they reduce the levels of other minerals in the plant vascular systems.
Rainwater is not always so helpful to plants, and is not available all the time. Hence, you need alternate sources to ensure healthy growth of your plants. If you have access to distilled or reverse osmosis water, you can water your plants with water from these sources. Water purified in these processes is pure and nourishing to the plants.
There may be no right or wrong choice here. The thing you must consider is which source of water will be most beneficial to the plants. Keeping this in mind, most often rainwater can suffice–after all, the rain forests depend entirely on rain. In case you have to use tap water, one way to reduce the adverse effects is to keep it overnight to allow ions to settle down and some of the chemicals to evaporate.