Why might rainwater be good for the garden?
Unless you live in an area where the air is highly polluted with excessive amounts of nitrates or sulfites (acid rain) or chemicals from industry, rain is a good thing for the garden. For the most part it will contain chloride, nitrates, sulfates and some phosphate. During runoff into your container of the nitrates will be converted to a gas that will be released into the atmosphere. If stored uncovered for a few hours, some of the chloride will also disperse.
Although I have no recipes for rainwater, I do want to discuss its makeup and compare it to city water.
Both city water sources and rain can contain a variety of nutrients, naturally occurring chemicals and bacteria from human and agricultural activities.
In areas of the world where large amounts of wood are burned for fuel and agricultural practices manage tons of fertilizers and livestock manures, rain can contain higher levels of contaminants.
A Carleton College study on Rainwater Chemistry Across the United States, found that rain on the East and West Coasts usually has higher concentrations of chloride from ocean water evaporation. Go to Rainwater in the Bibliography to read the study.
Rainwater must be stored carefully to reduce bacteria levels and potential contamination by heavy metals. How stringent your safety methods should be depends on what you’ll be using the water for. If you’ll be drinking the water, seek out official resources to ensure you’re employing safe procedures.
If you’re using rain to water the garden, it’s important to keep it covered so that mosquitos can’t use it as a breeding ground. Use it as soon as you can to avoid bacteria buildup.
Rainwater Quick Tips
- Rainwater that runs from your roof into a collection barrel can contain contaminants. If you are concerned about this, see the Bibliography in the back of the book for a link to a 2012 study published in the International Journal of Engineering and Technology. The researchers compared different roofing types and their impact on the composition of rainwater.
- We don’t get a lot of rain in Southern California. At the school garden, our water comes from a hose. We devised a primitive way of cutting down on the chlorine by filling buckets with water and letting them sit overnight. After several hours most of the chlorine evaporates. You can do this at home too.