You wanna see a wild scene?! Get a glimpse of my family scrambling to move the plants outside when we get a good rain for the first time in a while. We've got all the doors open and are running in and out to get our plants quenched with that precious rain water. The kids usually take the back door plants and the adults focus on lining up the plants out front. It's a wet and wild mess, but we have fun doing it.
Why so wild, you say?
We make it a strong effort partly because we can water so many plants at once (and we have a bunch!), but mostly because rain is arguably the healthiest way to irrigate your plant collection. The rainwater is free from additives that are often found in tap water, and naturally contains more beneficial elements and micronutrients. In addition to healthier ingredients, the pace of delivery (except for heavy downpours) allows the roots and growing media to drink slowly and saturate more thoroughly.
Water with rainwater when possible, but if not, allow your tap water for rest for 24 hours to allow some of the more harmful ingredients to evaporate as well as letting the water to acclimate to room temperature. Notably cold or hot water can shock and stress the your plants.