Part 6 – Water Supply

6.4    Design Requirements

Tables 1 and 2 from SNZ PAS 4509:2008 are copied below and form part of the design requirements for water reticulation.

6.4.1    Water Demand and Pressure

The water supply system shall be designed for the worst case flow and pressure requirements.  In most subdivision design, the fire fighting requirements will control the design.  The designed network should be checked to ensure that the annual, seasonal and peak demands are met using the available pressures in existing mains.  Calculations supporting the proposed design are required.

6.4.2    Domestic Supply

The design shall provide for a domestic demand of 260 litres/person/day with a peak flow rate of five times this amount.  A population density of 45 persons per hectare shall be the basis of the design.

6.4.3    Commercial and Industrial Supply

The water demand for commercial and industrial areas shall be analysed and specifically allowed for in the design.

6.4.4    Fire Fighting Supply

The water reticulation shall be designed to comply with the New Zealand Fire Service Fire Fighting (2008) requirements as shown in Table 1 and Table 2 which are copied from the manual.  Designs shall meet the requirements with regard to fire fighting flows, running pressure and the spacing of hydrants, together with any additional requirements set out herein, including storage where applicable. In addition designs shall provide for a minimum flow to each hydrant of 25 L/s flowing as a single hydrant test with residual flow pressure of 100 kPa.

Unless stated otherwise in a subdivision, land-use or building consent, the minimum fire fighting water supply classification shall be as follows:

• Detached or semi-detached housing in suburban areas    FW2
• Schools, local suburban shopping areas and equivalent development    FW3
• Commercial and Industrial areas    FW4

Note:  Designers should be familiar with New Zealand Fire Service Fire Fighting Water Supplies Code of Practice (SNZ/PAS 4509:2008).

6.4.5    Design Basis

Details of the working pressure or pressures at the point or points of connection to the existing reticulation can be obtained from Council.   These details shall be used for design purposes

6.4.6    Pipe Working Pressures

The minimum acceptable pipe class in the Matamata-Piako District Water Supply Areas is PN12.

Note:  Council hold the maps showing these areas.

6.4.7    Pipes

Pipes for water reticulation shall be uPVC, Ductile Iron or Polyethylene. 

Note:  The MPDC Infrastructure Code of Practice provides a useful guide and reference to standards.

Table 1- Method of determining required water supply classification (click to enlarge)

Table 2- Method of determining firefighting water supply (click to enlarge)

Appendices B, H, J & K are contained in New Zealand Fire Service Firefighting Water Supplies Code of Practice. SNZ PAS 4509:2009