Programme Description

WaterTest is an inter-laboratory proficiency programme for water chemistry laboratories. With more than 60 participants in 6 countries, the WaterTest programme has been designed to enable valid comparisons between results from laboratories engaged in research, industry, environmental or public health testing. Participants use a wide range of tests and methods, and may aim to achieve quite different limits of detection or analytical accuracy and precision. Contact us to discuss your laboratory's requirements.

Sample Description

WaterTest samples are comprised of three types:

Potable: drawn from natural sources. The water sample may be ground water, surface water or prepared from reticulated municipal water. Trace elements may have been added to supplement the natural mineral profile.

Synthetic: prepared from reticulated municipal water by distillation, followed by polishing and micro-filtration. Concentrated solutions of inorganic salts and metal standards are added to simulate a natural mineral profile.

Effluent: prepared from meat, dairy & municipal effluent streams. In order to meet our specification for concentration of the various key analytes one effluent sample is normally collected pre-treatment and the other sample is collected post-treatment.

In each proficiency round, participants receive two bottles for sample A (1x1 litre, 1x250ml) and two bottles for sample B. The A and B samples will have slightly different profiles.

Timetable - 2007/2008

Scope of testing

Participating laboratories analyse the samples only for those analytes they routinely test in samples of that type. Laboratories have a free choice of tests and methods. The scope of WaterTest includes the following tests:

WaterTest Reporting

WaterTest uses an internationally recognised statistical protocol. Before calculation of the Assigned Value or measures of dispersion, the data set for each test type is screened using the Dixon outlier test, and extreme values are removed from the data. The Assigned Value is calculated as a screened mean where n>20, otherwise the median is used. A standard deviation is calculated, and results which deviate from the Assigned Value by more than 2 Standard Deviations are identified in the Concise Data Summary.

The Proficiency Report is comprised of the following sections:

Concise Data Summary - a one page summary of your laboratory's performance across all tests for which results were returned. This makes checking your results quick and easy.

Confidence Limit Summary - uses the confidence limit reported by your laboratory to provide a check of your performance relative to your own expectations. By advising your own expected performance limits , you will receive independent reporting of your lab's performance.

Overall Data Summary - a summary of the statistics for all tests in the current round - including tests for which your laboratory has not submitted results.

Analyte Summaries - results for each analyte are presented on a separate page summarising your laboratory's result in comparison to the results of other participants. Detailed information on detection limits and performance of other laboratories are presented in a format which enable you to place your own interpretation on the proficiency results, and what follow-up action is most appropriate.

Annual Report - annually we also prepare an individual report summarising performance over the year across all the samples and range of concentrations. This report helps to identify limitations to performance and trends over time.