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Note: (i) The water demand data adopted for design purposes should be
based on a projected value, say 20 years hence. The data provided
in the table allow for rising standards of living and are the actual
figures anticipated for the year 2000, based on a 2% per annum
compounded growth. The tabulated information applies to
townships with flush sanitation and one or more taps in the yard, or
inside the building. Upper limits refer to high income townships and
the lower limits to lower income townships.
(H) Residential zone I implies one dwelling house and an outbuilding per
erf (normally the largest residential category in a town), while
residential zones 11 and III include multiple dwelling-unit buildings up
to three storeys high (excluding a basement). Residential zone IV
concerns high rise multiple dwelling-unit buildings of four storeys and
more. The design criteria are based on residential sites (erven) of
less than 2000 m 2 . For erven larger than 2 000 m 2 , demand should
be determined as per local conditions.
(iii) Demand data for categories 1 • 3, include garden watering of all
common areas outside the limits of the buildings.
(iv) The gross floor area is obtained using the applicable floor space ratio
derived from the relevant town planning scheme.
(v) Water demand for developed parks (category 9), must be considered
as being drawn over six hours on any given day, in order to obtain
the peak demand. Where the designer anticipates the development
of parks and sports grounds to be of a high standard (25 mm of
water applied per week), the annual mean daily water demand should
be taken as: S2ha-50kt; >2ha S10ha-40 kt, and >10ha
- 30 kt.
(vi) In order to calculate instantaneous peak flow rates, the various types
of development and consequent design demand should be converted
to standardized "equivalent erven", where the annual mean daily
demand is assumed to be 1 000 t per equivalent erven.
(vii) Reservoirs (with a gravity or pumped supply from one water source),
should have a minimum storage capacity of 48 hours of the annual
mean daily demand. Where the reservoir has a gravity or pumped
supply from two water sources, a minimum storage capacity of 36
hours is recommended.
(viii) The water supply system for emergency or temporary low cost
housing should consist of standpipes with 15 mm nominal size taps
situated in street reserves, with approximately one tap for every 10
houses, or located within 75 m of a given house. The total daily
demand for the township should be based on a demand rate of 5 kl
ha- 1 day-1 for the gross developable area of the township.