Dinking Water FAQs

Drinking Water Testing FAQs

1. Can I & How do I collect by own Drinking Water sample?

If you desire, you may collect your own drinking water sample; we can supply all the materials are instructions for doing so.

Obtain a Drinking Water Sample Collection Kit from Murray-Brown Laboratories containing:

Record the following information in your on-site sample log book and on the MBL Drinking Water Sample Submission Form:

  • Name of system (PWS site identification number, if available)
  • Unique Sample Identification (if any, as indicated on the PWS Monitoring Plan, i.e. “Bathroom Sink”)
  • Sample Site Location (including physical address)
  • Sample type (i.e. Routine Compliance, Repeat Compliance, or Special Purpose Non-Compliance)
  • Date and time of collection
  • Analysis requested
  • Disinfectant residual, if applicable (samples for compliance purposes)
  • Name of sampler
  • Any remarks

Following the Sample Collection Instructions, aseptically collect and transport the sample.

 

2. How do I select the site & faucet to collect my Drinking Water Sample? What is a Low Contamination Risk Faucet?

Selecting what faucet, including its type, location, and the water source which feeds it, to collect a water sample from depends upon why the sample is being collected.

  • If the sample is being collected for compliance purposes under the Total Coliform Rule, then the purpose is to test the water distribution system NOT the plumbing of an individual building.  Therefore, all precautions should be taken to eliminate collecting a sample which may yield a positive result due to the potential for contamination some sampling sites have by selecting a Low Contamination Risk Faucet (see blue box below).
  • If, however, the sample is being collected for non-compliance purposes from a production facility or home to assess water which may be directly consumed by humans, or come into contact with goods destined for human consumption, then the sample must be collected from a representative tap which supplies such water, no matter its condition.  If such testing does reveal the presence of coliforms and/or E. coli, it would be appropriate to conduct an investigation to determine the cause, develop, and implement appropriate corrective action, and follow up with repeat samples to confirm the success or failure of the corrective action taken.

Faucet Selection for Samples Collected for Compliance Purposes

The TCR requires each small community drinking water system to sample for coliforms according to a written plan, (PWS Monitoring Plan) which must be made available to the CDPHE.  Having a written sample collection protocol helps ensure that all sampling is done correctly, even when assignments of water system personnel change.

The plan specifies where in the distribution system routine samples will be drawn in order to ensure that they are “representative” of the water supplied to every customer.  Representative samples that accurately reflect the quality of the finished water are crucial because, if coliforms are in the water supply, they may not be found uniformly throughout the distribution system.  The sampling plan also designates repeat sampling sites to be used if a sample drawn from a routine sampling point tests positive for coliforms.  The purpose of sampling is not to draw “clean” samples, but to identify any coliform contamination so it can be dealt with promptly.  Because of this, it is important to identify dead ends and trouble spots in the distribution system for sampling locations.

When defining the Plan, sampling site locations, including specific faucets, which, according to their location or condition, have a high potential for contamination should be avoided as they may result in a positive result that is not truly representative of the water quality in the distribution system:

Low Contamination Risk Faucet

Water taps used for sampling should be free of aerators, strainers, hose attachments, mixing type faucets, purification devices, and should be in good repair (no leaks).  Avoid collecting samples from kitchen or utility sinks with swing arm necks, or from swivel-type faucets that have a single valve for hot and cold water.   It is not a good idea to collect water samples from:  new plumbing & fixtures or those repaired recently; outside taps or hoses, faucets that have leaky packing material around the stem; faucets that supply areas, such as janitorial or commercial sinks, where bacterial contamination is likely; faucets close to or below ground level; faucets that point upward; faucets that have treads on the inside of their spouts; faucets connected to cisterns, softeners, pumps or pressure tanks.

References:

CDPHE TCR Best Sampling Practices — Drinking Water Sample Collection Techniques.

  Open PDF

EPA Developing a Sample Siting Plan — How to develop a Sampling Monitoring Plan and how to determine sampling sites.

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EPA Sample Collection Techniques — An overview of drinking water sample collection with images.

  Open PDF

EPA Ground Water Rule Sample Collection & Transport:  A Quick Reference Guide — An overview of ground source water collection; page 2 details shipping instructions for samples.

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EPA Quick Guide to Drinking Water Sample Collection — General Sampling Procedures; Proceed to Total Coliform Rule.

  Open Link

 

 

3. Will MBL collect my drinking water sample for me?

MBL is qualified to collecting drinking water samples for both compliance and non-compliance purposes which are to be analyzed for total coliforms and E. coli.

Upon request and by appointment, MBL can collect drinking water samples if you so desire.

If you are a Public Water System, you must provide the exact sample location according to your Monitoring Plan, including the Site Name and Site Address.

Please contact us to discuss the price and availability of this service.

4. How do I determine the Chlorine Residual of my water prior to collecting a sample?

Sample Collection Requirements From EPA Manual for the Certification of Laboratories Analyzing Drinking Water:

  • Public water systems need to measure residual disinfectant concentrations with an EPA approved method.

EPA Analytical Methods Approved for Drinking Water Compliance Monitoring under the Disinfection Byproducts Rules — Proceed to Combined, Free, or Total Chlorine.

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HACH EPA Compliant Methods

  Open Link

5. How do I investigate a total coliform positive result in my drinking water sample?

Below are links to various investigational resources you may use to aid in determining the root cause for a total coliform positive in a drinking water sample.

EPA Distribution System–>Water Quality and the Distribution System (see resources at bottom of page).

  Open Link

EPA Small Systems Guide to the Total Coliform Rule

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CDPHE Total Coliform Rule Compliance

  Open PDF