The Drinking Water Inspectorate (DWI) has suggested that potable water distribution is an area of weakness in UK "source-to-tap" monitoring. Quality is rarely monitored on-line, but usually via analysis of grab samples. Interpretation of analytical results from such samples is often difficult, particularly for microbiological parameters, which may not reflect current conditions and have long analysis times.
Dissolved Oxygen (DO) is an alternative parameter that can provide information. Past studies show that DO can be used as an indicator of microbial growth, with reductions in DO between treatment and tap of 25% through microbial oxygen use. Reductions in DO, can also be linked to areas of active corrosion, particularly if flow is slow or stagnates. Increases in DO can be directly linked to air ingress (e.g. during rehabilitation) and formation of "white water" (micro bubbles when water is drawn from the tap).
DO is therefore a potential indicator of quality change - especially if it is linked to existing information (complaints, metal, analysis) and a specific network understanding. Cost-effective and reliable instrumentation for measuring DO at distribution pressures is available, and with remote communications technology, this could provide a powerful yet simple means of monitoring water quality in distribution.
This work evaluated the potential of DO to provide real time information on significant microbiological, chemical and physical water quality changes in distribution.
- A highly cost-effective approach to increasing security during distribution while reducing reliance on results from grab sampling
- Ability to identify quickly, and react to, changes in water distribution quality and hence reduced risk of compliance failures / customer complaints.