This tool calculates your surface water
Microbial Water Quality Profile (MWQP). Per the PSR, a minimum of 20 samples are required to obtain a valid MWQP.
Initial MWQP:
1. Collect at least 20 water samples that are representative of use and collected as close as is practical to harvest. These samples must be collected over a minimum period of 2 year(s), and not greater than 4 year(s).
2. Analyze water samples to quantify generic
E. coli/100 ml (usually by a testing service).
3. Enter water sample collection date in the first text box below.
4. Enter water sample collection location description or ID in the second text box.
5. Select the sample stage as
Initial.
6. Enter
E. coli lab results (
E. coli CFU/100ml o MPN/100ml) in the fourth text box.
Note: If your sample result is below the limit of detection at LOD <1 (or zero) generic E. coli CFU/100ml o MPN/100ml), enter 1.
7. Add
Notes if necessary (eg. rainy day, cloudy water, low flow). Press "Add"
Note: Samples will appear by date in Table 1.
8. Repeat step 3 to 7 until you have entered 20 samples.
9. Review each table to determine your Geometric Mean (GM), Statistical Threshold Value (STV), and compliance with Produce Safety Rule (PSR) requirements:
a. Table 1: Displays Your Microbial Water Quality Profile (MWQP) in the bottom two rows. The GM and STV are your MWQP.
b. Table 2: Displays Your MWQP Results Compared to the PSR microbial water quality criteria.
c. Table 3: Determines if your MWQP meets PSR criteria and if microbial die-off is required. Table 3 will only appear after one or more samples have been added.
Following establishment of your initial MWQP, update your MWQP
annually as follows:
1. Collect at least 5 water sample(s) that are representative of use and collected as close as is practical to harvest.
2. Analyze water samples to quantify generic
E. coli/100 ml (usually by a testing service).
3. Enter 5 current year sample values as described above in Step 3 to Step 7. For
Sample Stage, choose
Annual instead of Initial.
4. Review each table to determine your Geometric Mean (GM), Statistical Threshold Value (STV), and compliance with Produce Safety Rule (PSR) requirements:
a. Table 1: Displays Your Microbial Water Quality Profile (MWQP) in the bottom two rows. The GM and STV are your MWQP.
b. Table 2: Displays Your MWQP Results Compared to the PSR.
c. Table 3: Determines if your MWQP meets PSR criteria and if microbial die-off is required. Table 3 will only appear after one or more samples have been added.