Source Water Options: Selecting the Right Water for Your Dental Practice
Dental water quality is paramount for ensuring the safety of both patients and staff, but not all water is created equally. The water used in your dental unit plays a critical role in the performance of your water treatment products, ultimately affecting waterline safety and it even impacts equipment longevity.
Selecting the appropriate water source for your practice requires considering more than just convenience. This article covers the main types of water sources, their main benefits, and key considerations when selecting which type to use in your operatories.
The Importance of Source Water in Dentistry
Dental unit waterlines (DUWLs) are narrow, slow-moving pathways that provide an ideal environment for biofilm growth. Water that goes into a dental chair with potable bacteria levels (<500 CFU/mL) is not guaranteed to stay at that level because the environment is so conducive to bacteria proliferation. Even sterile water will become contaminated once exposed to bacteria in the waterlines and air. Some water types even contain the very nutrients bacteria love to eat, further propagating the problem. Ultimately, every source water type used in dentistry must be used in conjunction with some form of dental water treatment product and/or regular shock products.
There are many effective dental water treatment products on the market, and many of these state specific source water requirements. Some treatment product chemistries are not compatible with certain types of source water, and these incompatibilities can inhibit the product’s ability to keep your waterlines clean. Maintaining the EPA drinking water standard (≤500 CFU/mL), which has been adopted by the CDC as the minimum water quality requirement for dental water, involves more than just treating your waterlines; the water source itself must be safe for dental operations and compatible with your treatment plan.
The Best (and Worst) Source Water to Use
We’ve summarized key recommendations in the table below. For a detailed look at each water source type and several others, continue reading. The important thing to know is that there is no one size fits all. It is important to evaluate what will work best for your office, and Agenics Labs water experts are here to help.
Living vs Nonliving Contaminants
Living contaminants, such as bacteria, are microorganisms that can multiply and form biofilms within dental unit waterlines (DUWLs). These microorganisms are measured in terms of colony-forming units (CFU). Bacteria pose significant infection control risks and can compromise patient safety. Non-living contaminants, on the other hand, include minerals like calcium or chlorine, particulates, and other substances that do not reproduce but can affect the performance of water treatment products and equipment longevity. Total dissolved solids (TDS) is a key measurement of some non-living contaminants that can impact dental water treatment.
Drinking water is required to be treated to contain less than 500 CFU/mL, and in dental, we’re trying to keep the water below that level. TDS, on the other hand, is only recommended by the EPA to be below 500 parts per million (PPM), which means some source waters may have very high levels of TDS.
Comparison of Dental Water Sources
Purified Drinking Water
Source: Municipal supplies, wells, or surface water that is tested before being treated by validated methods. Purification and disinfection processes are used to substantially reduce the microbial and contaminant content.
Pros: Very clean and consistent water source that is regulated by the FDA and meets the definition of the U.S. Pharmacopeia. Easily accessible and affordable. 21 CFR165.110
Cons: Bottled water requires time and money to maintain a supply and space for storage. If using a dispenser, regular cleaning must be performed to ensure bacteria and biofilm are not building up in the unit.
Use: Ideal for all water delivery systems and antimicrobial treatment products except for products specifically designed for high TDS water.
Verdict: Recommended
Reverse Osmosis Water
Source: A semi-permeable membrane restricts small particles including dissolved solids and some microorganisms from flowing on. The clean water moves past the filter and the restricted particles are drained off in what is called ‘brine’.
Pros: Very clean; low mineral and microbial content. Consistent water quality that reduces chances of inhibiting interactions with treatment products and significantly reduces hard water deposits and/or mineral build up on dental equipment. Comparatively affordable on-site treatment systems available and filters can last up to and beyond one year.
Cons: Needs regular monitoring and maintenance. RO filters may have slow flow rates, which can limit water supply for dental facilities; storage tanks are used but can harbor bacteria.
Use: Ideal for bottle-fed and direct-feed systems when combined with antimicrobial treatment products such as straws, tablets, cartridges, or routine shock. Suitable for practices with high water demand.
Verdict: Recommended. May want to consider buffering and verifying pH & TDS. Look for high volume, tankless options.
Note: While RO water can be slightly acidic and has low TDS, it generally is not as pure as distilled or DI water and has a slightly higher alkalinity level. This increased alkalinity makes the water less reactive, reducing its likelihood to corrode or negatively affect dental equipment. Just in case, we recommend buffering RO water with a splash of tap water to obtain a TDS above 10ppm. Check your TDS with an affordable handheld meter. Check the pH of your water after adding your treatment product with a simple pH test strip. Generally, a pH between 6.5 to 8.5 will be safe. You will also automatically receive TDS and pH measurements for every sample in any Agenics mail-in test kit!
Distilled Water (bottled or generated)
Source: Boiling water, collecting the steam, and condensing the steam back into liquid form, leaving behind contaminants
Pros: Very clean; low mineral and microbial content. Consistent water quality that reduces chances of inhibiting interactions with treatment products and significantly reduces hard water deposits and/or mineral buildup on dental equipment. Can be purchased or generated on-site. Commonly used in autoclaves.
Cons: Bottled water requires time and money to maintain a supply and space for storage. Distiller devices must be maintained and continually operated to produce water. Inherently lower pH may be damaging to dental equipment, particularly when combined with a treatment product that further reduces pH.
Use: Ideal for bottle-fed systems when combined with antimicrobial treatment products such as straws or tablets. May be used in direct feed systems when combined with an antimicrobial treatment product but should not be used if copper plumbing is in place.
Verdict: Recommended when buffered and pH & TDS are verified.
Note: The purity of distilled water combined with a low pH and near-zero alkalinity, means it can be a ‘hungry’ water that may corrode some dental equipment components over time. We recommend buffering distilled water with a splash of tap water to obtain a TDS above 10ppm. Check your TDS with an affordable handheld meter. Check the pH of your water after adding your treatment product with a simple pH test strip. Generally, a pH between 6.5 to 8.5 will be safe. You will also automatically receive TDS and pH measurements for every sample in any Agenics mail-in test kit!
Deionized (DI) Water
Source: De-ionization resins inside of cartridges or tanks attract negative and positive ions (dissolved solids like chlorine and magnesium) as the water flows by. Eventually, the resins become saturated and stop removing ions.
Pros: Low mineral content reduces chances of inhibiting interactions with treatment products and significantly reduces hard water deposits and/or mineral buildup on dental equipment. Commonly used in autoclaves.
Cons: DI systems can be costly for small practices and require regular monitoring and maintenance (changing filters/cartridges). DI water starts with a relatively neutral pH but can drop when exposed to air. Lower pH levels can be corrosive to equipment, particularly when combined with a treatment product that further reduces pH. Ultra-pure DI water may not have the necessary ions to pull enough antimicrobial agent (such as iodine or silver) out of straws.
Use: May benefit from additional disinfection such as UV prior to being used in conjunction with an antimicrobial treatment product. May be used in bottle-fed or direct-feed systems.
Verdict: Recommended when buffered and pH & TDS are verified or used in a direct feed system.
Note: The purity of DI water combined with a low pH and near-zero alkalinity, means it can be a ‘hungry’ water that may corrode some dental equipment components over time. We recommend buffering DI water with a splash of tap water to obtain a TDS above 10ppm. Check your TDS with an affordable handheld meter. Check the pH of your water after adding your treatment product with a simple pH test strip. Generally, a pH between 6.5 to 8.5 will be safe. You will also automatically receive TDS and pH measurements for every sample in any Agenics mail-in test kit!
Municipal Tap Water
Source: Treated at large public water treatment facilities and commonly contain residual disinfectants (typically chlorine or chloramine).
Pros: Affordable and easily accessible. Regulated by the EPA.
Cons: Contains minerals, sanitizers, and microbiological impurities that can feed biofilm. Highly variable and subject to environmental changes such as construction or outside contamination. Can change seasonally, making consistent treatment product performance difficult to predict. May contain bacteria levels above the EPA limit. High chlorine levels can inhibit the performance of common treatment antimicrobials, including iodine, silver, and peroxide.
Use: Should be filtered to remove non-living contaminants and disinfected to bring down bacteria levels before being used in conjunction with a water treatment product. Most suitable for use with controlled dose treatment products such as tablets and liquids. Straw and cartridge performance is more susceptible to changes in the water.
Verdict: Only recommended if regular source water testing is completed. Can be included in regular treatment water testing.
Note: Every Agenics mail-in test automatically includes pH and TDS measurements!
Spring or Artesian Water
Source: Sourced from a natural spring and transported to a facility for treatment (usually filtration and some disinfection method). Residual disinfectants are generally not added to spring water as it would alter the taste and character of the water.
Pros: TDS level may be ideal for some treatment straws and cartridges. Neutral pH and better taste profile.
Cons: Expensive compared to other bottled water types and requires space for storage. While bacteria levels are usually brought below 500 CFU/mL at the treatment facility, the lack of residual disinfectants means the bacteria levels can increase over time. Even worse, spring water contains many minerals and nutrients that feed bacteria, making this a difficult source water to predictably treat and maintain.
Verdict: Not Recommended.
Additional Tips for Selecting and Managing Water Sources
Combine Line Maintenance with Water Source
No single water source guarantees safety. All water types must be combined with routine antimicrobial treatment.
Regular Evaluation
Verify the effectiveness of your treatment and water source combination by sending samples to laboratories like Agenics or using in-office tools. Periodically testing your water source in addition to your treatment is a great way to proactively monitor possible source water issues.
Use Self-Contained Bottles
These simplify treatment and allow you to control the source water, rather than relying on direct plumbed municipal systems that can vary throughout the year.
Educate Your Team
Ensure everyone involved in maintaining units or filling water bottles understands the type of water to use and how to treat it.
Guidelines and Recommendations
CDC: Surgical procedures should be performed with sterile water; non-surgical procedures should use water that meets EPA drinking water standards. Source
ADA: Advocates the use of self-contained water systems following treatment plans. Distilled and treated RO water is strongly recommended. Source
Conclusion
The safety of dental unit waterlines is built on the quality of the water supply. The water you put into your dental unit directly impacts the performance of your overall waterline management program. Compliance ensures safe water and patient trust; selecting the appropriate source—and combining it with proper maintenance—is crucial. Understanding the quality of your source water and how it interacts with your treatment products and dental equipment can feel overwhelming. Know that Agenics is here to help with key water quality metrics included in every sample result (CFU, TDS, pH) and comprehensive chemistry analysis services. By assessing your water quality and treatment product performance, we can provide guidance on what will work best for your specific office.
Start with clean water for safe patients. Make your water source a priority, not an afterthought.
Ready to prove your lines are safe? Order a mail-in test kit at Agenics.net. Results in as quick as 24 hours, plus free pH and TDS data for every sample.