http://www.harvesth2o.com/rainwater_safe.shtml#.VSLuf5_D_qAqA
- Is rainwater safe? To shed light on the issue, I performed a set of water quality tests. Water from a cistern and an adjacent well in Lamy, New Mexico were tested. Additionally, I compared these samples to city water from my new home city of Santa Fe, New Mexico.
Water was drawn directly from the cistern and well (i.e. prior to any treatment) on the same day and sent to the National Testing Laboratories to be tested in accordance to their procedures. These samples I then compared to Santa Fe’s published Water Quality report. Most water districts publish this information as it is required by the Environmental Protection Agency (EPA).
Comparing the cistern water to the well water, it is clear that cistern water is better or equal to the well water; except that the cistern has a presence of coliform.
Coliform, a bacteria, is frequently found in streams, lakes, ponds, cisterns; and
may indicate the water is contaminated with other harmful bacteria. Systems used for drinking water should always have some type of sterilization process (See related article on UV Sterilization of Rainwater Catchment Systems) to kill bacteria and organisms such as coliform.
Not so surprisingly
there is a huge difference in hardness, calcium, and alkalinity between the well water and the rainwater. Well water typically drains from underground water tables and is normally stored in natural underground tanks; so it will slowly leach minerals and metals from the surrounding ground. Consequently, well water will generally have higher mineral and metal content depending on local soil conditions. In comparison, rain water will not have these issues, but may be adversely affected by local air pollution and debris in the rainwater catchment and conveyance areas (i.e. roof, gutters, downspouts, and pipes).
