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WINZ Item: 1014 Status: Archive Written: 4 November 2002

Quarterly Compliance and Protozoa - Worked Example

This article works through an example of completing the Protozoa tab for plant quarterly compliance in WINZ. It is presented here because the currently on-screen Help may not make it clear to users which aspects are auto-calculated and which are derived through answering questions.


To complete a Quarterly Compliance Record for a treatment plant in WINZ, you need to answer some questions about barriers to protozoa, in accordance with the NZ Drinking Water Standards, Section 3.2.3.

To go to this area in WINZ: Main Menu -> Compliance -> Plant Monitor tab -> Protozoa tab. (You will need to have added a quarter record in order to see the details discussed.)

The WINZ screen is as follows:

There are four ways to meet the Protozoa Compliance Criteria, named a, b, c and d. These are accessible by clicking on the "Protozoa Criteria" drop-down box.

For our example, we will use Protozoa Criteria b. Note that some criteria may not be appropriate, and hence not selectable, for some supplies.

Working through the Criteria b Example

There are a lot of different option combinations on the Protazoa page, and WINZ is probably a bit lean on explanations as to what is covered and what is still up to the user to determine. Basically, WINZ doesn't determine criteria b compliance from first principles. By knowing how many manual turbidity samples, turbidity levels, number of filters, etc., it could in theory work out compliance. But this is beyond the capability included here in WINZ, so instead it does the following:

1. WINZ doesn't know how many filters, so the requirement for criteria b is listed for one filter only.

2. WINZ determines the "Turbidity for Quarter" statistics (screen top right), but presents these for guidance only. It does not do compliance calculations based on these.

3. WINZ determines the population and uses this as the basis for determining the shown requirements towards the bottom of the screen.

And that is all WINZ currently does in this area.

Then YOU must answer the questions, ie

1. Max turbidity 100% of the time. This should be 0.89 for your samples - Wairoa has 0 entered. (Use the magnifying glass in the Turbidity for Quarter to seee results.
(Note that, as a general WINZ compliance principle, text boxes that take entries have a 3-D sunken appearance while read-only calculated values appear in flat boxes.)

2. Max 95% time. You have only 15 results so maybe you could say 0.66 here. (This in itself will then calculate criteria b = non-compliance on the next recalc, but read on ...)

3. You must now say whether meets minimum measurement frequency of 184 per Quarter. Since you have only 15 samples, enter N (not Y).
As explained, the 184 ignores the number of filters. For 5 filters and a pop of 5001-10000, table 3.4 in the Stds says twice a day, with at least one turbidimeter per 2 filters. Therefore you need 184 x 3 = 552 results for quarter minimum.

4. Similarly, 95% of results are not below 0.5 NTU, so you should answer N to the next question.

5. Recalculation will now confirm that criteria b is not met.

When this area was developed it was decided that many people may not enter all these samples into WINZ, but they do need a way to check their compliance with more detail than a single yes/no question. Hence the questionnaire-type approach on this page, with the "Turbidity for Quarter" statistics and result viewer available for extra assistance.

If you have any questions or feedback on this article, please contact Barry Mattingley at ESR.



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