Disinfection is a critical stage in the water well drilling process. During drilling, the well is exposed to surface contaminants, soil bacteria, and potential pathogens from drilling fluids and equipment. The failure to properly disinfect a water well—both during construction and during routine maintenance—leads to a cascade of mechanical, chemical, and biological failures. These problems are generally categorized into Operational Risks (damage to the well structure and equipment) and Water Quality Risks (risks to the consumer, product or process).
Operational Risks (Well Infrastructure)
Without proper disinfection, a well can become heavily contaminated. Bacteria introduced during drilling or pump repair thrive in the dark, steady-temperature environment of the aquifer.
1. Bio-fouling and Clogging
The most common operational problem is the growth of Biofilms. Certain bacteria produce “Extra-cellular Polymeric Substances” (EPS)—a thick, snot-like slime.Biofilms in Water Systems — Formation, Impacts, and Advances in Control Through Continuous Chlorination Strategies
• The Result: This slime coats the well screen (the intake) and the gravel pack surrounding it.
• Impact: Water cannot easily enter the well. This leads to a “loss of specific capacity,” meaning you have to pump harder to get the same amount of water, eventually causing the well to go “apparently dry” despite water being present in the aquifer.
2. Microbiologically Influenced Corrosion (MIC)
Bacteria such as Iron-Oxidizing Bacteria (IOB) and Sulfate-Reducing Bacteria (SRB) do not just live in the water; they actively “dissolve” or chemically alter metal surfaces.
• The Result: These bacteria create localized acidic environments under biofilms.
• Impact: This causes rapid pitting and holes in the steel well casing and the pump components. A pump that should last 15 years may fail in 3–5 years due to MIC.
3. Pump Burnout
As bio-slime clogs the well screen, the “drawdown” (the drop in water level during pumping) increases.
• Impact: The pump has to work against a higher Total Dynamic Load (TDL). Additionally, the slime can coat the pump motor, preventing it from dissipating heat into the water. This leads to electrical failure and motor burnout.
Water Quality and Contamination Risks
Even if the well is mechanically sound, the water it produces can be dangerous or unusable for industrial processes or municipal drinking water without disinfection.
1. Pathogenic Contamination (Health Risk)
This is the most critical risk. Wells can be contaminated by:
• Bacteria: E. coli, Vibrio cholerae, and Salmonella.
• Viruses: Hepatitis A, Norovirus (often introduced by surface water runoff or nearby septic failures).
• Protozoa: Giardia and Cryptosporidium.
Problem: Pathogens are incorporated within an existing biofilm. Biofilm provides a mechanical and chemical shield that protects them, allowing contamination to persist and intermittent releases into the water flow to occur for years. Without the disinfection these pathogens can establish a “home” in the well’s gravel pack and be released into the water supply intermittently for years.
2. Aesthetic and Sensory Issues (Taste/Smell)
Bacteria change the chemistry of the water, leading to “off-flavors” that are unacceptable in the beverage industry or for municipal use.
• Rotten Egg Odor: SRB convert naturally occurring sulfates into Hydrogen Sulfide (H2S) gas.
• Metallic Taste: IOB dissolve iron from the casing and the soil into the water, causing a bitter, metallic taste and staining laundry or plumbing fixtures orange.
• Slime Chunks: In severe cases, chunks of white or grey biofilm can break off and enter the water stream, clogging downstream filters and UV systems.
3. Nutrient Spikes and Chemical Evolution
A “dirty” well can undergo “Redox” changes. Bacteria can trigger the release of arsenic or manganese from the surrounding rock into the water through metabolic processes.
Niche Problem: For soft drink bottlers, ammonia produced by certain bacteria in a non-disinfected well will react with chlorine later in the process to form Chloramines, which have a powerful “chlorine” odor that ruins the taste of beverages.
4. Total Coliform/E. coli Rule Violations
From a regulatory standpoint, a non-disinfected well will fail to meet the Revised Total Coliform Rule (RTCR).
• Problem: In many jurisdictions, a single “positive” test for E. coli requires the immediate shutdown of the well, a “Boil Water Advisory” for the public, or the total halt of production in a bottling plant. This results in massive financial losses and reputational damage.
Summary Table: The Cost of Neglect
| CATEGORY | PROBLEM | OPERATIONAL / HEALTH IMPACT |
| Mechanical | Bio-slime Clogging screens | Reduced water yield; Higher energy costs |
| Electrical | Motor Overheating | Frequent pump replacements ($5,000 – $50,000+) |
| Chemical | H2S gas production | Rotten egg smell; corrosive to pipes |
| Biological | Biofilm “Seeding” | Constant source of bacteria that bypasses standard filters |
| Regulatory | Positive Coliform tests | Fines, plant shutdowns and legal liability |
Water Well Disinfection Using NSF 60 registered Organic Chlorine
NSF 60 certification strictly validates the purity and safety of the chemical used so that it can come into contact with drinking water.
Suggestion for a proper disinfection process:
1. Scope and Application
Three specific scenarios:
• New Well Construction: Before the well is put into service.
• Well Service/Repair: After a pump has been pulled, the casing repaired, or the well deepened.
• Contamination Events: Following a flood or a positive coliform test in an existing well.
2. Approved Disinfectants
The accepted industry standard requires that all chemicals used for disinfection meet ANSI/NSF Standard 60 (Drinking Water Treatment Chemicals).
3. Key Procedural Requirements
A summary for compliance:
| STEP | REQUIREMENT |
| Preparation | Well must be physically clean/flushed |
| Chemicals | Must be ANSI/NSF 60-61 certified |
| Concentration | Minimum 50 mg/L throughout the well |
| Contact Time | Minimum 12 hours |
| Flushing | Pump until chlorine residual shows <0,2 mg/L |
| Verification | Two consecutive negative coliform tests (24 hrs apart) |
PROVICHLOR TABLET™ is an excellent alternative for water well disinfection
Organic chlorine is increasingly used as an alternative disinfectant to traditional inorganic chlorine (liquid bleach or calcium hypochlorite) due to its stability, high concentration, and ease of transport. How Organic Chlorine Delivers Reliable Water Disinfection — Without the Operational Burden
NSF 60 – approved PROVICHLOR TABLET™ is a unique organic chlorine formula that has a proven and powerful performance as a disinfection agent and has significant advantage over other chlorination alternatives, for example, it does not drastically alter the pH, it does not clog filters with calcium deposits, it has a longer shelf life, and it is safer during transport.
| FEATURE | PROVICHLOR TABLET™ | INORGANIC CHLORINE (SODIUM HYPOCHLORITE) | INORGANIC CHLORINE (CALCIUM HYPOCHLORITE) |
| AvailableChlorine | High (58 – 65%) | Low (10 – 12%) | High (65%) |
| Stability | Excellent | Poor | Low |
| pH Influence | Neutral (pH 7) | High (pH 11) | High (12) |
| Solubility | High | Liquid form | Moderate (leavesscale/residue) |
| Storage Hazard | Low (Solid tablet) | High (Corrosive Liquid) | High (Oxidizer/Fire risk) |
Conclusion
Disinfection of water wells, whether new or in operation, is essential for proper well operation and the quality of the extracted water. Correct, continuous and consistent disinfection guarantees trouble-free well operation in the long term.
Well proper disinfection isn’t just about killing bacteria today; it’s about preventing the colonization of the well structure, which ensures the long-term “health” and productivity of the well for decades.
PROVICHLOR TABLET™ is an excellent choice for water well drilling disinfection due to its neutral pH and chemical stability. Unlike Calcium Hypochlorite, it does not contribute to scaling or “clogging” of the well screen, and unlike liquid bleach, it does not lose its strength during storage at a hot drill site. It provides a reliable, high-potency “kill step” to contribute to the safety of new and operating water sources.