Microsoft Word - WaterChemistry

451

Common Water Quality and Sampling Statements

All of these suggestions are not official law, please double check

with your state drinking water or health agency before

implementation

1. What are the correct procedures to follow in collecting bacteriological samples?
   Use a sterile plastic or glass bottle. Sodium thiosulfate should be added to neutralize the
   chorine residual. Refrigerate the sample to 4o C. The regulations call for a minimum of
   five samples for the month from any system that has positive sample results. Small
   systems that take only one sample per month have to take four (4) repeats when they get
   a total coliform positive test result. If any system has to take repeat samples, it must also
   take a minimum of five (5) routine samples the following month. Small systems that
   normally take less than 5 samples/month will have to increase the number to 5 samples.
   They can return to normal sampling schedules the following month if no repeats are
   required.


2. What are the proper sampling techniques for microbiological sampling?
   Proper sampling techniques are extremely important in obtaining accurate water quality
   information. An improperly taken coliform sample may indicate bacteriological
   contamination of your water when the water is actually safe. You can avoid the cost of
   additional testing by using good sampling procedures. Carefully follow these steps in
   taking a sample for bacteriological testing:


3. Select the sampling point. The sampling point must be a faucet from which water is
   commonly taken for public use.
    The sampling point should be a non-swivel faucet.
    Remove any aerator or screen and flush.
    It should not be a faucet that leaks, permitting water to run over the outside of the
   faucet. Leaking faucets can promote bacterial growth.
    If an outside faucet must be used, disconnect any hoses or other attachments and
   be sure to flush the line thoroughly.
    Do not use fire hydrants as sampling points. Do not dip the bottle in reservoirs,
   spring boxes or storage tanks in order to collect the sample.


4. What do the following abbreviations stand for and what do they mean: gpm,
   MGD, TTHM, psi, HAA, NTU, and mg/L.
   Gallons per minute- Million Gallons a Day - Total Trihalomethanes – Pounds Per Square
   Inch –Haloacetic acids - Nephelometric turbidity unit -Milligrams Per Liter


5. What is the relationship between mg/L and ppm; ug/L and ppb?
   Milligram per liter: Milligram per liter of substance and part per million are equals
   amounts in water. While you can easily convert between micrograms/liter and
   milligrams/liter, and between PPM and PPB, its not so easy to convert between the
   different types of units such as milligrams/liter to PPM.

To convert micrograms per liter to milligrams per liter, divide by 1000.