Rainwater Harvesting Health & Safety Considerations Jason Feltham Public Health Inspector Calgary Health Region

Non-potable Purposes Untreated collected rainwater appropriate for non-potable purposes only. –Toilet flushing, laundry, irrigation, outdoor washing (eg. building exterior, vehicles, pets) –Fire protection –Does not include dishwashing, handwashing, bathing or dental care.

Non-potable Plumbing Rainwater plumbing separate from potable water supply. –Back-flow prevention devices in place at any cross connections (air gap between potable water supply inlet and rain cistern water level) Color-coded plumbing to easily identify non-potable supply. Preliminary wash of rooftop before collection commences, or screen to remove leaf litter, dirt, etc.

Non-potable Signage Signage on outdoor fixtures: Not safe for human consumption. –Hose bibs –Irrigation connections

Challenges & Possible Problems Challenges for non-potable rainwater systems: –In absence of treatment - amplification of Legionella, Pseudomonas, bio-films –Backflow / backsiphonage events –May be corrosive to plumbing materials due to aggressive chemical nature of rain water (lower pH, lack of hardness) –Operation & maintenance by qualified personnel –Nuisance issues: odor, color, staining, algae, stagnant plumbing (dead ends)

Presence of known human pathogens –Rooftop will have feces of animals such as birds & rodents –Salmonella, Campylobacter, Cryptosporidium, viruses –Rooftop temperatures and UV exposure will serve to reduce levels of microorganisms Still risk of pathogen exposure Rain Water for Human Consumption - Health Concerns -

Prevent insect and small animal access to any water storage, eg. Mosquitoes Rooftop materials do not leach chemicals, toxic substances, eg. CCA-treated wood Rain Water for Human Consumption - Health Concerns -

Airshed pollutants? –Not likely to see chemical contaminants in rain water at levels exceeding established drinking water guidelines Area-dependant: Proximity, density, and type of industrial activity Weather-dependant: Forest fires, inversions Rain Water for Human Consumption - Health Concerns -

Airshed pollutants –Calgary has excellent ambient air quality (comparatively speaking) Owing to it’s location & lack of heavy industry Vehicular pollution major contributor Particulate matter contains many things (eg. Heavy metals such as lead and mercury) Rain Water for Human Consumption - Health Concerns -

Airshed pollutants –Also ‘Leap Frog Effect’ Airborne pollution this side of the equator migrates Northward, in water vapor of atmosphere. Heavy metals, pesticides, dioxins, hydrocarbons, etc. –Issue may be with health effects of long-term, low level exposure to chemical contaminants through ingestion of rain water.

Preliminary treatment to remove dirt, leaf litter, particulate matter, etc., and/or divert first several minutes of rain to waste, before collection commences. Would require a disinfection process for the destruction of micro-organisms (bacteria, viruses, protozoa) –Continuous chlorination –Ozonation Rain Water for Human Consumption - Treatment -

Disinfectant-resistant protozoa –Cryptosporidium may be present Geese & ducks act as mechanical vectors of C. parvum, and can be reservoirs of C. meleagridis which can also infect humans Could require treatment to remove/destroy disinfectant-resistant protozoa Filtration (Absolute 1 micron) or UV –Immuno-compromised individuals especially at risk of illness. Rain Water for Human Consumption - Treatment -

Other options include –Reverse Osmosis Extremely wasteful & energy-costly –Distillation Energy costly Will serve to both disinfect the water and reduce any chemical contaminants that may be present. Could be achieved through either central treatment or with Point-of-Use devices. Rain Water for Human Consumption - Treatment -

Regular testing of any disinfectant residuals Regular sampling of treated water (weekly) Qualified personnel for operation & maintenance of system (cleaning of reservoir, treatment equipment, etc). May require Alberta Environment approval if serving a communal system or public facility

Rain Water Harvesting Good opportunity to study rainwater use for domestic purposes –Volume of water –Microbiological quality, including presence of known human pathogens –Nuisance issues – odor, color, staining, algae, stagnant plumbing, etc. –Chemical quality – significance of airshed pollutants –Effectiveness of treatment systems and advances in sustainable design concepts

Rain Water Harvesting in Calgary Two applications have come through our office for comment. –Rain will be sole supply of water for entire subdivision Adequate volume? Treatment to render safe for human consumption Proposed point-of-use devices –Changed proposal so use restricted to non-potable purposes

Rainwater Harvesting in Calgary –Second proposal was a residential/commercial development –Non-potable use (toilets and outside irrigation) –Planned to chlorinate water collected in cistern and top up with City supply as needed

Questions?