LEED CERTIFICATION Water Harvesting is very important due to: Conservation of Water Lowering Depletion of Natural Resources & Materials Creating a Sustainable Site Use of Innovative Design LEED points > http://www.whollyh2o.org/daily- stream/item/430-leed-certification-and-water- harvesting.html
Components of Rain Harvesting CATCHMENT AREA/ROOF GUTTERS & DOWNSPOUTS LEAF SCREENS & ROOFWASHERS – to remove debris & contaminants (ex. Plantboxes) CISTERNS or STORAGE TANKS CONVENYANCE – delivery system (gravity or pump)* *more on the gravity pump (BBC winner) TREATMENT – filters, additives, (recall schmutzdeck)
Water Savings Potential (RainwaterHarvesting) Dependent on: (1) catchment area , (2) storage capacity, (3) annual rainfall, (3a) seasonality of rainfall 1500 sq-ft (139.35 sqm) roof = 934 gallons (~3,500 L) from 1” rainfall > 20” annually = 18,680 gallons (13,248 L) > storage tanks must have corresponding capacityhttp://www.world-climates.com/city-climate-metro-manila-philippines-asia/
Irrigation Options Gravity Feed or Pump; Manual or Automatic Manual Irrigation – preferred for small systems: hose bib >> bottom of rain barrel; much less expensive & easier to maintain Drip Irrigation – in dryer regions: storage tank >> gravity fed drip system; must be filtered to avoid clogging of drip channels Automatic Irrigation – complex system of pumps, irrigation emitters/sprays, for LARGE RWH systems
IMPORTANT CONSIDERATIONS Metal roofs > best catchment; if painted, must be with non-toxic paint (paints w/ no lead, chromium or zinc) Overhanging vegetation must be avoided > may clog roof gutters/etc Tanks: tight-fitted and with screens to avoid mosquito nesting, prevent debris/critters from entering tank; screens must be regularly cleaned; OPAQUE to prevent algal growth Gravity is preferred over pump
IMPORTANT CONSIDERATIONS Roof, gutters, downspouts > clear of leaves, branches, debris. Note > overhanging branches = bird perching = droppings. Cleaning at frequent intervals Irrigation system must be checked for leaks, blocked emitters Rainwater may be used not only for toilet & irrigation, but with sufficient filtering, may actually be used for washing.
GREYWATER untreated used household water that does not contain human wastes – washing/rinse water, water from bathtub, sink, shower Up to 40 gallons per person per day (average) Used mainly for toilet flushing, irrigation of non-food landscape (ornamental plants only; meaning it may not be used for organic garden) Dual plumbing = expensive; more effective if they are incorporated into the construction of a new home but probably not for modifying an existing home.
GREYWATER SYSTEMCOMPONENTS Dual-plumbing > collect water from desired sources Three-way valve to divert contaminated water or excess water to sewer or septic system Treatment system > *more in next slide Holding tank Pump or Gravity-Fed distribution system
GREYWATER SYSTEMS: TREATMENT Aerobic Pre-treatment > to filter off large debris, good for bathtub, shower, washing machine > not for kitchen sink. Commercial version: Clivus greywater management fabric filter configuration, Willa eco- matic Anaerobic treatment prior to aerobic pre-treatment >> needed for sources with food waste/organic particles Planter soilbox design >> in use in 1975 w/ excellent results
Two types: Water-injection system that prevents soil erosion Gravity or pressure leaching chamber http://www.greywater.com/treatment.htm > more details
GREYWATER SYSTEMS COSTING Low-tech: 200 micron mesh (filter) + 55 gallon tank w/ locking lid = $400-800 (P17-35K) Medium-tech: 200 micron mesh + 2 x 55-gal tanks + sump pump + subsurface drip irrigation = $1,000-1,500 (P43-65K) Fully-automated installation: pumps, 3-way valve, backflow control, etc, up to 250 gal capacity = $2,500 – 5,000 (P100-200K)
NOTES/TIPS/MAINTENANCE Highly beneficial for landscape irrigation Determine which plants will be irrigated with greywater. Simpler installations are usually more successful & offers better ROI Secure tanks from mosquitoes, algal growth, debris Efficient Irrigation design must consider sufficient percolation but NOT excessive flow to avoid erosion Stored greywater MUST NOT LEAVE your property > septic tank; meaning not good for flood-prone areas.
RECOMMENDATIONS WRT MADE Ideal for landscape irrigation, toilet flush Rainwater harvesting preferred over greywater reuse Data is available on storage/output volume estimates, monthly rainfall in mm so we can compute Gravity pump may be used in conjunction with the system With reservoir + gravity pump = water flowing through interior regularly = aesthetics + passive cooling Further research = ferro-cement (used in tanks?)