General Sampling Information for Drinking Water Systems in Wyoming and on Tribal Lands in EPA Region 8
On this page:
- Certified Labs
- Regulated Analytes
- Accuracy of Sample Results
- Sampling Plans
- Sampling Equipment and Techniques
- Sample Bottle Labeling
Sampling is necessary to ensure that the drinking water you produce meets the drinking water standards for your system. It is also used to determine if your system is operating the way it should be operating. You also need to monitor the treatment techniques used, primarily filtration or approved alternatives to filtration for surface water systems.
Each year, we at EPA Region 8 send out your system's monitoring and reporting requirements schedule for that calendar year. We may provide additional details or changes to you by mail during the year. The reporting requirements listed indicate the sampling points and locations for sampling. The Monitoring Requirements Guide provides additional information on how to use your monitoring and reporting schedule, plus helpful tips for sample collection, chain of custody, etc. The schedule takes into account EPA's Standardized Monitoring Framework (PDF).
One way to track your sampling and reporting requirements is by using the calendar software on your computer. Computer calendars usually allow you to schedule one-time and recurring events easily. You may also set the computer to remind you of a sampling or reporting "event". If you prefer to fill in a paper form and post it on your bulletin board, you may find this Sampling Calendar useful. The sampling calendar is also available in MS Excel format(1 page, 22 KB).
You may also sign up to receive sampling reminders by email from our office. This sign-up option is provided in the side-bar menu after you have registered and logged into Drinking Water Watch .
However, EPA Region 8 will notify you of specific requirements for your system in the Monitoring and Reporting Requirements mailed to your system early each calendar year, and may provide additional details or changes in correspondence during the year.
EPA approves the analytical methods that laboratories use to analyze drinking water samples and also certifies the laboratories. You must use a laboratory certified to analyze the kind of samples that you send them. We cannot accept results from a laboratory that is not certified to analyze for each contaminant in your samples. If this occurs, we will reject the results and your system will be considered as having failed to monitor and report.
Please see EPA Region 8 Certified Drinking Water Laboratories for a list of labs currently certified to analyze samples taken at Wyoming or Region 8 Tribal public water supply systems.
National Primary Drinking Water Regulations (NPDWRs or primary standards) are legally enforceable standards that apply to public water systems. Primary standards protect public health by limiting the levels of contaminants in drinking water. Here is a List of Regulated Analytes(1 page, 58 KB) enforced by EPA Region 8 in Wyoming and Indian Country.
For details on permitted levels of these contaminants and the potential health effects from long-term exposures above permitted levels, please check Drinking Water Contaminants – Standards and Regulations.
Accuracy of Sample Results
Maximum Contaminant Levels (MCL) contained in the National Interim Primary Drinking Water Regulations are expressed in the number of significant digits permitted by the precision and accuracy of the specified analytical procedure(s). Data reported to the State or EPA should be in a form containing the same number of significant digits as the MCL. In calculating data for compliance purposes, it is necessary to round-off by dropping the digits that are not significant. The last significant digit should be increased by one unit if the digit dropped is 5, 6, 7, 8 or 9. If the digit is 0, 1, 2, 3, or 4, do not alter the preceding number. For example, the MCL for nitrates is 10 mg/L, which is two significant digits. Therefore, a result of 10.2 is rounded down to 10 mg/L and a result of 10.5 mg/L is rounded up to 11 mg/L.
For more information about approved analytical methods, please visit Methods Approved to Analyze Drinking Water Samples to Ensure Compliance with Regulations.
You should have sampling plans for the microbial, physical, and chemical sampling and monitoring that you perform in your public water supply system and distribution system. These plans should specify the location of sampling points, the frequency of sampling, procedures for sampling, and record keeping and reporting requirements for each type of sample or monitoring event(s). You must provide EPA Region 8 with copies of your sampling plans and with modifications made over the course of time.
EPA Region 8 provides written guidance on preparing sampling plans and will answer questions that you may have regarding their preparation and modification. Please contact the appropriate Rule Manager on our EPA Region 8 Drinking Water Section Contact List with your questions.
Sampling Equipment and Techniques
We suggest that you contact the laboratory with which you do business to determine the kind of sampling material you should use and how you should deliver samples to them. The laboratory may provide you with sample bottles and preservatives. After taking a sample, be sure to write down the sample point and location, record the date and time the sample was taken, follow the chain of custody procedures, store the sample at the appropriate temperature, and deliver the sample to the lab within the time limits for that sample. You can find general information about what is required in the Quick Guide To Drinking Water Sample Collection document. However, your laboratory may have additional instructions that you should follow.
Sample Bottle Labeling
The way you label your water samples tells the EPA Region 8 Drinking Water Section a lot about the sample, whether you mean it to or not. It also determines whether your sample results will be credited to your water system, or if you end up with a monitoring violation if the correct sampling location is not clearly indicated. Drinking Water Sample Bottle Labeling explains how to clearly and correctly label your drinking water samples in order to receive the credit you deserve.
Each system is responsible for ensuring we receive monitoring and sampling reports on time. You may have an arrangement with your laboratory to send a copy of the results directly to our office, but you are still ultimately responsible for reporting.
- Ten calendar days following the end of a month
- Total coliform (no presence) when required to sample monthly (If adding chlorine, the chlorine residual must be measured and reported for the same time and location as Total Coliform samples)
- Turbidity monitoring
- Chlorine residual at the entrance to the distribution system
- Maximum residual disinfectant levels (MRDL) at the same time and same place as total coliform sampling
- Stage 2 Total Trihalomethanes (TTHMs) and Haloacetic Acids (HAA5s) sampling quarterly (results and LRAA form) are due on the 10th day following the month of your required sample
- Stage 2 TTHM/HAA5 monitoring annually or tri-annually for are due on the 10th day following the month of your required sample
- Ten calendar days following the end of a calendar quarter
- All quarterly sampling results (except quarterly TTHMs/HAA5s)
- DBP precursor (total organic carbon, alkalinity and removal ratios)
- Chlorite sampling results
- Bromate sampling results
- Ten days following the end of any other monitoring period, whether six months, one year, three years, or more
- Other deadlines as specified by circumstances, such as for composite samples
Acute health violations, such as for positive total coliform and for nitrates require 24-hour notification to EPA Region 8. Please call the appropriate rule manager directly if our offices are open. If our offices are closed, please leave a message at telephone number 1-303-312-6327.
If the laboratory you use sends your sample to another laboratory for analysis, you need to submit the sample results page(s) from the laboratory doing the actual analysis, as well as the report your laboratory transfers to its report. Remember to keep copies of your monitoring and sampling results and the reports you send to our office.
You will find more details about reporting and can obtain the appropriate forms at our Reporting Forms page.