Rainwater Harvesting Health & Safety Considerations

1. Rainwater HarvestingHealth & Safety Considerations Jason Feltham Public Health Inspector Calgary Health Region

2. Non-potable Purposes • Untreatedcollected 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.

3. 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.

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

5. 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)

6. 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

7. 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

8. 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

9. 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)

10. 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.

11. 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

12. 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.

13. 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.

14. 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

15. 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

16. 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

17. 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

18. Questions?