The green boxes, or sample stations, provide designated sampling sites to retrieve potable water samples at any time (24/7) versus sampling directly from homes or businesses. Currently, the PWSD laboratory staff sample sixty sites for one level of testing for Colorado Department of Public Health and Environment (CDPH&E) drinking water compliance. All of these sites are from customer hose bibs. As the population increases, more sample sites are necessary to meet the regulation. Sample sites are chosen to be representative of the entire distribution system.
Concerns exist with sampling from customer homes. Homeowners frequently install water treatment systems that void the use of the site. Not all customers tell the District about changes to their plumbing system in a timely manner. Additionally, by the nature of the work, landscape and hose bib damage can occur even though staff are conscientious and careful to respect private property.
In addition, sampling stations have been shown to produce lower false positives for bacteriological samples, decrease sample collection time, and reduce liability concerns. Sample Stations are approved for use by the EPA’s Total Coliform Rule.
As the District moves forward with the change to chloramination, numerous distribution sample locations will be necessary to test for signs of nitrification. Finally, it is important to note that not all water line locations that we feel should be sampled have residences available to solicit permission to allow sampling hose bibs.
The new sample station is non-draining to reduce possible contamination and comes standard with surgical steel waterway and lockable cast-aluminum enclosure. The unit is non-freezing with the use of a manual evacuation hand pump.