WATER SERVICES
Disinfecting a new water service: the chlorination steps
A brand new water service is not ready to carry drinking water until it has been disinfected. The process is straightforward, but the residual and the hold time are where it has to be right.
Why disinfection is required
New pipework picks up debris and contamination during install. Before it supplies drinking water, it is flushed and chlorinated to bring it to a safe standard. For larger services the procedure steps up again.
The fill-and-hold method
In short: flush the service clean at a good flow velocity, then fill it with chlorinated water at the required free-chlorine concentration and hold it for the specified retention period. After the hold, the residual is checked to confirm the disinfection held throughout the service.
Residual and hold time
- Achieve the required free-chlorine concentration at the start.
- Hold for the minimum retention period for the method used.
- Confirm a free-chlorine residual is still measurable across the whole service at the end.
Bigger mains call for the storage-tank or AWWA procedure rather than the residential method.
What to record
Note the flush, the concentration, the hold time, and the measured residual, ideally with the test in shot. Elemetric keeps that alongside the job photos.
Common questions
Why disinfect a new water service?
New pipework picks up debris and contamination during install. It is flushed and chlorinated before it supplies drinking water to bring it to a safe standard.
What chlorine residual am I aiming for?
Achieve the required free-chlorine concentration at the start, hold for the minimum retention period for the method, then confirm a free-chlorine residual is still measurable across the whole service.
Document the next job in minutes
Your first five jobs are free, with no card to set up.
Download on the App Store →General information for licensed tradespeople, not legal or regulatory advice. The licensed plumber remains solely responsible for compliance. Refer to the current AS/NZS 3500 standards and the Building and Plumbing Commission (formerly the VBA) for authoritative requirements.