Rainwater Harvesting Health Safety Considerations Jason Feltham Public

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 p. H, lack of hardness) Operation & maintenance by qualified personnel Nuisance issues: odor, color, staining, algae, stagnant plumbing (dead ends)

Rain Water for Human Consumption - Health Concerns • 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.

Rain Water for Human Consumption - Treatment • 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 -potable purposes non

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?