Do I Need to Treat Rainwater Before Storing in a Tank?

Pre-Treatment Considerations

Before storing rainwater, consider the roof’s material, as it can leach contaminants into the water. For example, roofs with asphalt shingles can shed oil and tar, while metal roofs may shed heavy metals. Use a first flush device, which diverts the initial flow of water from the roof, to minimize contamination risk.

Treatment Methods

To effectively treat rainwater, use a combination of physical, chemical, and biological processes. Start with coarse filtration (about 1/4 inch mesh size) to remove debris and sediment. Follow this with activated carbon filtration to remove chlorine, heavy metals, and other organic compounds. Ultraviolet (UV) light disinfection or ozone treatment can then be used to kill bacteria, viruses, and other microorganisms. Consider using a treatment system with a flow rate of at least 10 gallons per minute to ensure effective treatment.

Storage Tank Requirements

When storing treated rainwater, ensure the tank is made from a food-grade, corrosion-resistant material, such as stainless steel or polyethylene. Regularly inspect and maintain the tank to prevent contamination and bacterial growth. Consider adding a floating intake valve and a sedimentation chamber to improve water quality and reduce maintenance needs. Store treated rainwater in a tank with a minimum capacity of 1,000 gallons to allow for adequate turnover and treatment cycles.