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Example Calculation of Annual Cost of Chemical Compliance Sampling

How to use information from Texas Drinking Water Watch to calculate the annual chemical sampling cost for a typical public water system.

This example shows how to follow our steps for calculating the annual cost of chemical sampling for a public water system.

In the first step in this calculation, use Texas Drinking Water Watch (DWW) to find the sample schedules for your public water system. In DWW, a water system we chose at random had the tables of Group and Individual Non-TCR Sample Schedules shown below.

Which sampling schedules are open?

The Group and Individual tables for this water system show a total of 14 sampling schedules. One of these — the Lead/Copper schedule beginning in 2005 — is a duplicate and can be ignored. Whenever you see two schedules that are alike in every way except for the Begin Date, you may ignore the earlier one. (This is a bug, and we are working on getting it fixed.)

As for the other 13 schedules, under "Begin/End Date," we see:

  • Every End Date is labeled "Continuous" — in other words, none of these schedules are closed.
  • Every Begin Date is before 2012 — so each of these schedules has already begun.

From this information, we can see that this water system has 13 open sampling schedules. But how many are due in 2012?

Example schedules

Which sampling schedules are due this year?

To decide which of the open schedules are due, we must look under "Req's" for the sampling frequency. There we can see:

  • One QT (quarterly) — DBP Phase 1. This schedule is due.
  • No 6M (every six months). But if your water system does have any 6M schedules, those schedules are due.
  • Five YR (annually) — Minerals, Nitrate/Nitrite, Synthetic Organics, Volatile Organics, and Sodium. (Did you miss sodium? Remember to check for the table of Individual Non-TCR Sample Schedules!)

We can also see a number of schedules with less-than-annual sampling frequencies. For these open schedules, we must look at the Begin Date:

  • The four 3Y (every three years) schedules — Lead and Copper Rule, EDB/DBCP, SOC Method 515.4, and SOC Method 531.1 — have Begin Dates of 2008 and 2011. Because the Begin Date is not 2010, none of these schedules are due in 2012. (Remember that we ignored the duplicate Lead and Copper Rule schedule with a begin date of 2005.)
  • The two 6Y (every six years) schedules — Metals and Radionuclides —  have Begin Dates in 2006, not 2007. They were due last year — in 2011 — and will not be due again until 2017.
  • The only 9Y (every nine years) schedule, Asbestos, has a Begin Date of 2004. Because 9Y schedules that began in 2004 are due in 2012, this schedule is due. (Again, remember to see if water system also has a table of Individual Non-TCR Sample Schedules.)

How much will this year's sampling cost this water system?

To find out how much sampling will cost, first multiply these three numbers together for each type of sample:

  • The number of samples that must be taken each time this type of sampling is to be done under this schedule. Under "Req's," this is the first number that appears for that type of sample. (Ignore the "RT." It labels the samples as "Routine.")
  • The number of times this type of sampling must be done each year. This depends on the sampling frequency:
    • 4 for QT (quarterly)
    • 2 for 6M (every six months)
    • 1 for YR, 3Y, 6Y, and 9Y.
  • The lab fee for that type of sample.

For the water system in our example, these calculations are shown in two steps in columns 2 and 3 of this table:

Sample Type Number of Samples Lab Fee
Total Cost
DBP1 16 (4 x 4 quarters) $97.63 x 16 $1,562.08
MIN 1 $106.39 x 1 $106.39
NO32 1 $8.49 x 1 $8.49
SOC5 1 $205.41 x 1 $205.41
VOC 1 $55.12 x 1 $55.12
Sodium 1 $7.73 x 1 $7.73
Asbestos 1 $130 x 1 $130
Grand Total = $2,075.22

Finally, add up these totals for each type of sample to get the total sampling cost for the year. In the table above, this addition is done in the last column.

When you do your water system's calculation, you may use any spreadsheet or scratch pad you like.  Or you can use this Cost Calculation worksheet like the one shown above.

Have questions? Call us!

If you have any questions about your sample schedules or need help with these calculations, please call us at 1-800-447-2827.