Rainwater Harvesting Health

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Rainwater HarvestingHealth Safety
Considerations

• Jason Feltham
• Public Health Inspector
• Calgary Health Region

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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.

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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.

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Non-potable Signage

• Signage on outdoor fixtures Not safe for human
  consumption.
• Hose bibs
• Irrigation connections

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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)

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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

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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

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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

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Rain Water for Human Consumption- Health
Concerns -

• Airshed pollutants
• Calgary has excellent ambient air quality
  (comparatively speaking)
• Owing to its location lack of heavy industry
• Vehicular pollution major contributor
• Particulate matter contains many things (eg.
  Heavy metals such as lead and mercury)

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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.

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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

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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.

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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.

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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

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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

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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

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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

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Questions?