A sanitary survey includes a review of system integrity, supported by water quality data, particularly microbiology data.

A sanitary survey is defined in the Australian Drinking Water Guidelines as a review of the water sources, facilities, equipment, operation and maintenance of a public water system to evaluate its adequacy for producing and distributing safe drinking water.

This page forms part of the NSW Health response protocol for water utilities and public health units: Managing pathogen Risks in drinking water

The sanitary survey should determine whether system barriers are operating normally, particularly at critical control points (CCPs), and investigate and document the following:

Catchment management and source water protection

  • the integrity of critical catchment and storage protection such as fences and locked gates
  • whether there is high or rapidly changing raw water turbidity that cannot be improved (e.g. by changing the level of off-take or source)
  • whether there has been a recent inflow of water from a contaminated source in the catchment (even if raw water turbidity is stable). Sources could include sewer overflows, sewage treatment plant discharges or storm runoff from intensive agriculture.
  • whether there has been a recent natural event that may impact raw water quality e.g. storm event, flooding, fire
  • condition of extraction points for surface water sources (e.g. pumping station subject to flooding, inlet screen condition)
  • integrity of bore head structures and bore casing (consider whether contamination from the surface could enter the bore)
  • integrity of raw water transfer infrastructure e.g. pump stations and pipelines.

Water treatment plant performance

  • integrity and sources of contamination at treatment structures (e.g. coagulation, settling, clear water tanks, filters)
  • CCPs are meeting operational targets, particularly filtration (i.e. filtered water turbidity) and disinfection (i.e. disinfection contact time, C.t and residual)
  • power surges or loss of power supply
  • the water treatment plant(s) operational and CCP data from the preceding 24-48 hours.

Distribution system performance and integrity

  • maintenance of adequate disinfection residual (free chlorine residual of at least 0.2 mg/L or total chlorine of at least 0.6 mg/L in chloraminated systems). Where there is a risk of Naegleria fowleri (see NSW Health Naegleria fact sheet), free chlorine residuals must be at least 0.5 mg/L.
  • integrity of the distribution system, especially reservoir integrity
  • any recent main breaks, repairs or interruptions to supply
  • sudden changes in flow direction or surges in water supplied
  • potential for deliberate or accidental contamination
  • power surges or loss of power supply
  • continuing sample collection for operational monitoring (chlorine, turbidity, temperature and pH) and laboratory verification.

Note: Before flushing mains, consider the risk that flushing may distribute contamination throughout the system if the source of contamination is unknown.

Further information

Contact your local Public Health Unit on 1300 066 055 and refer to:

Current as at: Friday 8 February 2019
Contact page owner: Environmental Health