This is a controversial topic, here you will find a lot of the science and reports about 1080 in water supplies...make your own informed decisions
Exclusion areas are maintained around water supply intakes in accordance with rules established by the Ministry of Health and enforced by local district health boards. From the Ministry of Health's Guidelines for issuing permission for using vertebrate toxic agents:
The EPA 1080 reassessment decision document defines public drinking-water supply as includes drinking-water supply reservoirs, treatment plants and storage facilities. This definition is not exactly the same as the Health Act 1956, which uses the term ‘networked supply’, however the intent is the same. The Health Act defines a networked supply as “a drinking-water supplier who supplies drinking-water from the place where the supply is to one or more other properties, by means of a pipe connecting those properties ...”. In other words this definition also excludes self-supplies.
A private water supply is simply one that is privately owned (not used for profit). The Ministry understands that identifying private water supply sources is standard practice for more rural operations.
Public Health HSNO Enforcement Officers issuing permissions for the use of VTAs should consider the risk from the proposed application when they consider what conditions to include in the permission. This will include the type and location and nature of the water source (including volume if a creek or river or roof tank), number of people on the supply, distance from VTA application, etc. (from page 33)
NOTE: Similar consideration under MoH also applies to access points/tracks/huts
To read more on Guidelines for issuing permission for using vertebrate toxic agents please click HERE