VARIABILITY OF WATER QUALITY IN SMALL SUPPLIES 420-5 DOE Contract PECD 7/7/154
Report No DWI0041

Apr 1986

SUMMARY

If the standard of service is to be improved for the consumers of drinking water connected to small supplies, equipment is needed which will operate reliably under the conditions found at simple and remote sources. A limited range of equipment is available for disinfection at sources of reasonably steady flow and quality but further advances require better knowledge of the variations of flow and quality in the streams coming off small catchments.

In this first exploration in this area, the Department of the Environment commissioned WRc Processes to conduct a survey of literature and current research on the subject and to find out how much data existed in the records of the public supply undertakings.

No water quality records were found of the kind needed for treatment process control or design.

Although no research was discovered which gave the required information directly, two interesting models were found. The first was able to predict hydrographs on ungauged catchments requiring only a statement of initial Soil Moisture Deficit and information obtainable from a map of the catchment. The second offered a model of bacterial movements on a catchment.

It was concluded that although no model existed which would predict the variations of water flow and quality in small supplies, it would be possible to develop one straightforwardly from existing models. In the meantime the only way of assessing variability was by sampling campaigns.

Copies of this report may be available as an Acrobat pdf download under the 'Pre 2000 Reports' heading on the DWI website.