A drinking water system provides water for human consumption through pipes or other constructed conveyances. A drinking water system is a Public Water System (PWS) if it has at least 15 service connections or regularly serves an average of 25 or more people for at least 60 days per year.
A PWS can be one of three types:
- Community Water System – Serves at least 15 service connections or 25 people year-round in their primary residences (e.g., cities, towns, apartment complexes, and mobile home parks with their own water supplies).
- Nontransient Non-community Water System (NTNCWS) – Serves at least 25 of the same people over 6 months per year (e.g., schools, churches, factories, and hospitals that have their own water supplies).
- Transient Non-community Water System (TNCWS) – Serves an average of at least 25 people, but not necessarily the same people, over 6 months per year (e.g., campgrounds, rest stops, and gas stations that have their own water supplies).
Additionally, a PWS may be a consecutive system if it receives some or all of its finished water from one or more wholesale systems. Delivery from a wholesale system to a consecutive connection may be through direct connection or through the distribution system of one or more consecutive systems.
Where Does Drinking Water Come From?
Approximately 95% of the state’s drinking water comes from groundwater sources. The remaining 5% is supplied through surface water sources.
Safe drinking water is critical to individual and public health, understanding the quality of your drinking water and what actions to take if it is unsafe are important.
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Each year, community water systems in Idaho are required to prepare annual Consumer Confidence Reports for customers. These reports provide consumers with information on where their drinking water comes from and what is in it. Contact your water supplier for information on the latest report.
DEQ posts water quality data for all public water systems on the Drinking Water Watch application. This application will provide a summary of sample results and overall water quality provided by each system.
Public water systems are required to notify consumers if contaminant levels exceed Idaho’s drinking water regulations, if a waterborne disease outbreak or any other situation occurs that may pose a risk to public health, or the water system fails to test its water as required.
For serious issues, notification is required within 24 hours. For less serious issues, notification is required within 3 to 12 months (depending on the violation). Notifications will describe any precautions a consumer needs to take.
Boil water advisories may be issued by the owner or operator of a public water system or by DEQ. The advisory notifies water system users that the water may be contaminated with potentially harmful bacteria and to boil the water prior to use until further notice. The advisory will provide the reason for its issuance and describe the corrective actions being taken by the water system.
Small quantities of water can be disinfected through:
- Boiling: Boil water for 1 minute. To improve taste of boiled water pour it back and forth from one container to another multiple times, allow it to stand for a few hours, or add a small pinch of salt for each quart of water boiled.
Boiling should not be used if water contains elevated levels of nitrate, heavy metals, or other chemical contaminants. Boiling water with elevated level of contaminants will increase the contaminant concentration. If you have an elevated contaminant level, chemical disinfection should be utilized in lieu of boiling or an alternate source of water such as bottled water should be used.
- Chemical Disinfection: If boiling is not practical, chemical disinfection should be used. The two chemicals commonly used are chlorine and iodine. EPA’s Emergency Disinfection Procedures describe the appropriate products and processes for chemical disinfection.
Lead is rarely in drinking water when it leaves the source or treatment plant. Lead is typically introduced to drinking water by leaching into the water from some service lines and plumbing in buildings and homes. This is most prevalent in older structures that still have lead pipes or piping with lead solder. More information on lead in drinking water can be found on EPA’s website.
Community and non-transient non-community public water systems test their water for lead. Contact your water supplier to discuss sampling efforts and results for your system or building.
Bottled water is not necessarily safer than your tap water but is valuable in emergency situations. EPA sets standards for tap water provided by public water systems. The Food and Drug Administration sets bottled water standards based on EPA’s tap water standards. Bottled water and tap water are both safe to drink if they meet these standards. Consumers should carefully read the label to understand what they are buying with a focus on water source and treatment methods.
Most homes served by a public water system do not require additional treatment. If you have a private well, spring, or surface water intake, it is your responsibility to test your drinking water to ensure that it is safe. Consumers who choose to purchase a home water treatment unit should research several options to ensure your treatment needs will be met. No single treatment unit will remove every kind of drinking water contaminant. If purchased, follow the manufacturer-recommended operation and maintenance procedures and frequencies to ensure performance. DEQ recommends that any drinking water treatment unit meets American National Standards Institute/National Science Foundation (ANSI/NSF) standards. NSF provides a webpage to narrow your search based on contaminants of interest.
Whether you are served by a public water system or private well understanding the safety and quality of water you consume is important.
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Public water systems routinely test for common contaminants. If your home is served by a community water system, your annual water quality report will tell you which contaminants, if any, have been found in your drinking water and at what levels.
Independent sampling is typically at the sampler’s expense. Depending on how many contaminants you test for, a test can range from $15 to hundreds of dollars. Testing for all possible contaminants can reach into the thousands of dollars. If you are interested in independent sampling, identify what contaminants you’d like to test and obtain quotes from multiple labs. DEQ recommends using a laboratory certified to perform drinking water analyses. A list of certified laboratories can be found through the Idaho Bureau of Laboratories directory of labs.
You are responsible for ensuring that your private well water is safe to drink. Private wells should be tested for nitrate and coliform bacteria annually. Testing is not required, though it is recommended to protect you and your family. Contact your local health district to learn more about water quality and which contaminants you may need to test.
The Idaho Bureau of Laboratories maintains a directory of labs certified to test drinking water. Many of these labs offer sampling services for an additional fee. Identify what contaminants you’d like to test for and obtain quotes from multiple labs. The lab will provide you with sampling instructions and appropriate sample containers if you choose to perform the sampling yourself.
No, but the Idaho Bureau of Laboratories maintains a directory of labs certified to test your drinking water. Many of these labs may offer sampling services for an additional fee.
A maximum contaminant level (MCL) is the maximum amount of a contaminant that is allowed in drinking water to ensure that the water is safe to drink. MCLs are only applicable to regulated public water systems, but DEQ recommends private drinking water sources adhere to these contaminant levels. Water meeting the MCL standards is considered safe to drink.
Drinking water may present sight (i.e., discoloration or cloudiness) or smell (e.g., sulfur or chlorine) conditions that may be off-putting to consumers and raise safety concerns.
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Even when drinking water meets EPA standards you may still object to its taste, smell, or appearance. Some compounds such as iron and other sediments may give your water the appearance or smell of being dirty without affecting its health quality. If you think you have a problem with your water, contact your water supplier. If the system owner or operator is unavailable, contact your local DEQ regional office.
You can make the water more palatable by exposing it to the air for a few hours or by pouring it from one clean container to another several times. If there are concerns, contact your public water supplier.
Distribution system flushing or water main repairs can disturb sediments in water mains. This may result in a red- or brown-colored tap water. If your water is discolored, turn on a single cold water tap for several minutes to flush any sediment out of your building’s plumbing. If discoloration issues persist contact your water supplier.
Blue-green water could be an indicator or high copper levels. Contact your water supplier or your DEQ regional office for more information.
To protect public health, public water systems are required to develop and implement Cross-Connection Control (CCC) programs.
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Community water system purveyors are required to implement and enforce a cross-connection control program to prevent toxic or hazardous materials from entering the system. Programs must meet several requirements.
The purveyor must make sure that cross-connections either do not exist or are isolated from the water system by an appropriate backflow prevention assembly. Backflow assemblies must be inspected and tested annually by a tester licensed by the Idaho Bureau of Occupational Licenses.
A cross-connection refers to any actual or potential connection or piping arrangement between a public or a consumer’s potable water system and any other source or system through which it is possible to introduce into any part of the potable water system any source or substance other than the intended potable water with which the system is supplied.
- Bypass arrangements
- Jumper connections
- Removable sections
- Swivel or change-over devices
- Any other temporary or permanent devices or piping arrangements that can cause backflow to occur
Fixture protection is the practice of installing backflow prevention assemblies or devices to isolate one or more cross-connections within a customer’s facility.
Backflow – The reverse from normal flow direction in a plumbing system or water system caused by back pressure or back siphonage. There are two types of backflow: backpressure and backsiphonage.
Backpressure – Backflow caused by a downstream pressure that is greater than the upstream or supply pressure in a public water system. Typically caused due to an increase in downstream pressure, a reduction in the potable water supply pressure, or a combination of both.
Backsiphonage – Backflow caused by a negative pressure (i.e., vacuum or partial vacuum) in a public water system. Typically caused by a stoppage of water supply due to nearby firefighting, water main break, or routine maintenance flushing, or other situations causing a significant loss in water system pressure.
Although the water purveyor is responsible through its cross-connection control program to take reasonable measures to protect the water system against contamination and pollution from cross-connections, property owners have a responsibility to install and test backflow prevention assemblies in accordance with their purveyor’s program.
Connection control program to prevent toxic or hazardous materials from entering the system. Programs must meet several requirements:
- An inspection program to locate cross-connections.
- Required installation of suitable protection.
- Annual backflow assembly inspection and testing by a licensed backflow assembly tester.
- Ensure that assemblies that cannot pass annual tests or are defective shall be repaired, replaced, or isolated within 10 business days, otherwise water service to the failed assembly must be discontinued.
- Discontinuance of service for any facility where suitable backflow protection has not been provided for a cross-connection.
Backflow prevention assembly – A set of mechanical components that prevent the undesired backflow of non-potable water or other liquids into the potable water system. An assembly can be tested. Examples of assemblies include:
- Double check valve assemblies (DCVA)
- Reduced pressure principle backflow assemblies (RPBA)
- Spill-resistant vacuum breaker assemblies (SVBA)
- Pressure vacuum breaker assemblies (PVBA)
Backflow prevention device – A backflow preventer that does not meet the approval requirements of a backflow prevention assembly (i.e., is not testable):
- Residential meter check/single-check valve (CV)
- Dual-check backflow preventer (DCV)
- Dual-check with atmospheric vent (DCAV)
- Hose bib vacuum breaker (HBVB)
- Atmospheric vacuum breaker (AVB)
The purveyor must make sure that cross-connections either do not exist or are isolated from the water system by an appropriate backflow prevention assembly. Backflow assemblies must be inspected and tested annually by a tester licensed by the Idaho Bureau of Occupational Licenses.
We are often contacted to provide the compliance status of a public water system prior to closing on the sale of the property.
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To help DEQ provide information as quickly as possible, please contact the regional office where the public water system is located. Be prepared with the public water system’s name.
General information for public water systems, including sample results and violations, can be obtained from DEQ’s Drinking Water Watch application.
Contact the local health district for any private well sampling questions.
Visit our Water Sampling Resources page for how-to videos.
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Drinking Water Bureau Chief