Rainwater harvesting overflow discharge location - methods
Link to this table
| Overflow Discharge Locations / Methods |
Advantages |
Disadvantages |
| Discharge to grade via gravity flow (most recommended |
- Simplest method to design, install and operate
- Low probability of rainwater backing up the overflow drainage piping
|
- If discharge location not preparedd properly, may cause soil erosion at site
- May pose a nuisance/safety issue if discharging large volumes from big catchment surfaces.
- Overflow drainage piping may freeze if large sections are above the frost penetration depth; ice may build up at the point of discharge if not designed properly.
|
| Discharge to storm sewer via gravity flow |
- Ideal for below-ground tanks as storm-sewers are also located below grade.
- Storm sewers are specifically designed to collect roof runoff and direct it to an apprpriate location off-site
|
- Design must prevent backflow from storm sewer into rainwater tank.
- Stormwater discharges can have negative environmental impacts on recieving water bodies
|
| Discharge to soakaway pit via gravity flow |
- Permits the handling of stormwater on-site, which contributes to maintaining pre-development drainage regimes.
- Environmantal benefits of groundwater discharge
- In newer housing developments, an infiltration trench, serving multiple lots, may be built by the developer
|
- Soakaway pits require extensive site work to design and install (high in cost)
- Large rainfall events can exceed the infiltration capacity of the soil, requiring a separate overflow from the soakaway pit.
- Suitable only for permeable soils
|
