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<International Source Book On Environmentally Sound Technologies
for Wastewater and Stormwater Management>

6.3 Stormwater reuse

Stormwater is generally of a higher water quality than wastewater. Reuse (or strictly 'use' of stormwater can take place at two levels (household and municipal) or even at a larger (regional) scale if desired. Use at the household and municipal levels is described below.

6.3.1 Household level

Figure 2.45: Diverter for the first flush from roof run-off

Householders can use stormwater by collecting roof run-off in a tank for use as drinking water (common in arid regions), flushing toilets or for irrigation of the garden. The first flush of roof run-off can be contaminated by dust particles, leaf litter and animal droppings. The first flush can be simply diverted using a simple diverter (Figure 2.45). A screen can be placed at the inlet to the tank to filter gross particles. Water for drinking will still need to be boiled to denature pathogens.

Water from the roof can be directed to the garden beds directly rather than through soakways, and in this way shallow rooted vegetation can benefit from the water, especially in arid regions.

6.3.2 Municipal level

At the municipal level stormwater can be stored in ponds for use for irrigation of parks and gardens and for fire-fighting purposes. This is in addition to employing the ponds for flood control and for improving the amenity value of the water as described in Section 2 (4.3). Other uses are for groundwater recharge, either as a means of storing water, e.g. during the rainy season, for withdrawal in the dry season. Groundwater recharge can also be used to prevent encroachment of sea water near the coast where there is heavy groundwater withdrawal in excess of natural replenishment by precipitation.

Stormwater collected from community buildings (i.e. government and churches) may be stored in reservoirs to be used by the community during dry periods. This method is used in the Pacific SIDS atoll countries of Tuvalu and Kiribati.

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