SC By SCWS Team | January 18, 2025 | 9 min read
Well Chlorination Cost
Need to disinfect your well and wondering about the cost? Professional well chlorination typically runs $150-$500 for a standard shock treatment. This essential service eliminates harmful bacteria, addresses water quality issues, and is required after certain well work. Here's everything you need to know about well chlorination costs and when you need this service.
💲 Quick Cost Summary
- • Professional shock chlorination: $150 - $500
- • DIY shock chlorination: $20 - $50 (materials only)
- • Continuous chlorination system: $800 - $2,000 installed
- • Follow-up bacteria test: $30 - $150
- • Complete service with testing: $200 - $600
What Is Well Chlorination?
Well chlorination is the process of adding chlorine to your well system to kill bacteria, viruses, and other microorganisms. There are two main types:
Shock Chlorination
A one-time, high-concentration treatment that disinfects your entire well system—from the bottom of the well through all household plumbing. The chlorine sits in the system for 12-24 hours, then is flushed out. This is the most common type and what most people mean when they say "chlorinate my well."
Continuous Chlorination
An ongoing treatment system that injects small amounts of chlorine into your water supply continuously. Used for wells with persistent bacterial contamination that shock treatment alone can't solve.
Well Chlorination Cost Breakdown
Professional Shock Chlorination
| Service Component | Cost Range | Notes |
|---|---|---|
| Basic shock chlorination | $150 - $300 | Shallow wells (<150 ft), standard access |
| Deep well chlorination | $250 - $400 | Deep wells (150-400+ ft), more chlorine needed |
| Complete system treatment | $300 - $500 | Well + pressure tank + all plumbing + water heater |
| Pre-treatment bacteria test | $30 - $100 | Confirms contamination before treatment |
| Post-treatment bacteria test | $30 - $100 | Confirms successful disinfection |
Factors Affecting Cost
📊 What Affects Your Chlorination Cost
Well Depth
Deeper = More Chlorine
A 400 ft well needs 4x more chlorine than 100 ft
Casing Diameter
Wider = More Volume
8" casing holds more water than 6"
Static Water Level
Water Column Height
Determines actual water volume to treat
Plumbing Extent
More Pipes = More Time
Large homes with multiple bathrooms take longer
DIY Shock Chlorination Costs
If you're comfortable doing it yourself, shock chlorination materials are inexpensive:
DIY Materials Cost: $20 - $50
- Unscented household bleach (8.25% sodium hypochlorite): $5-$10 for 2-3 gallons
- OR well chlorination tablets: $15-$30 for enough to treat most wells
- Chlorine test strips: $8-$15
- Safety equipment (gloves, goggles): $10-$20 if not already owned
⚠️ DIY Considerations
While DIY chlorination saves money, improper treatment can fail to disinfect completely or damage well components. If you're unsure about your well's specifications, bacterial contamination source, or proper procedures, professional service is recommended.
Continuous Chlorination System Costs
For wells with persistent bacterial contamination, a continuous chlorination system may be necessary:
| System Type | Equipment Cost | Installation | Annual Chemical Cost |
|---|---|---|---|
| Basic chlorine injection | $400 - $800 | $200 - $400 | $100 - $200 |
| Proportional feed system | $600 - $1,200 | $300 - $500 | $100 - $200 |
| Complete system + carbon filter | $1,000 - $2,000 | $400 - $700 | $150 - $300 |
Learn more about ongoing treatment options in our UV vs. chlorine treatment comparison.
When Does Your Well Need Chlorination?
Not all wells need routine chlorination. Here are the situations that warrant shock chlorination:
Required Chlorination Situations
🔧 After Well Work
New well drilling, pump replacement, or any work that opens the well casing
🦠 Positive Bacteria Test
Coliform bacteria or E. coli detected in water sample
🌊 After Flooding
Flood water may have entered well or contaminated area
🏚️ Extended Non-Use
Seasonal properties or wells unused for months
🏠 Home Purchase
Often recommended when buying a home with a private well
👃 Water Quality Changes
New odors, tastes, or appearance may indicate contamination
Situations Where Chlorination May Help
- Rotten egg smell: If caused by sulfur bacteria (not mineral sulfur), shock chlorination can eliminate the odor. See our guide on sudden rotten egg smell.
- Iron bacteria: Creates slimy deposits and reddish-brown staining. Chlorination helps but may need repeated treatment.
- Slime in toilet tanks: Bacterial biofilm growth can be eliminated with system-wide chlorination.
The Well Chlorination Process
Understanding the process helps you know what you're paying for with professional service:
Step 1: Calculate Chlorine Amount
The amount of chlorine needed depends on:
- Well depth and casing diameter
- Static water level (actual water column height)
- Water stored in pressure tank and plumbing
- Target chlorine concentration (typically 50-200 ppm)
📐 Typical Chlorine Requirements
For a 6" diameter well with 100 feet of water:
- • Approximately 1.5 gallons of household bleach, OR
- • 3-4 well chlorination tablets
Amounts increase proportionally for deeper wells or larger diameter casings.
Step 2: Add Chlorine to Well
Chlorine is introduced directly into the well casing. Professionals may:
- Mix chlorine with water before adding to ensure distribution
- Use a hose to reach the bottom of deep wells
- Recirculate water to distribute chlorine throughout
Step 3: Distribute Through System
Chlorinated water is pumped through all household plumbing:
- Every faucet is run until chlorine smell is present
- Toilets are flushed to chlorinate supply lines
- Water heater is flushed (turning down temperature first)
- Outdoor spigots and irrigation if applicable
Step 4: Wait Period
The chlorine must remain in the system to effectively kill bacteria:
- Minimum: 12 hours
- Recommended: 24 hours
- For stubborn contamination: Up to 48 hours
🚫 Important: Do Not Use Water During Treatment
Highly chlorinated water is not safe for drinking, bathing, or watering plants/animals. Plan accordingly—this typically means starting treatment in the evening and flushing the next day.
Step 5: Flush the System
After the wait period, all chlorinated water must be removed:
- Run outdoor spigots or hoses away from septic and landscaping
- Continue until no chlorine smell remains
- Test with chlorine strips to confirm levels below 4 ppm
- Flush water heater last (may need draining)
Step 6: Post-Treatment Testing
Wait 7-14 days, then retest for bacteria. This waiting period allows any surviving bacteria to regrow to detectable levels, confirming whether treatment was successful.
DIY vs. Professional Chlorination
When DIY Makes Sense
✅ DIY Is Appropriate When:
- You know your well's depth, casing diameter, and water level
- You're comfortable working with chemicals and following safety procedures
- It's routine maintenance after minor work
- You have a way to safely dispose of chlorinated water (away from septic/plants)
- You can plan for 24-48 hours without water
When to Call a Professional
📞 Professional Service Recommended When:
- You don't know your well specifications
- Contamination source is unknown
- Previous DIY attempts didn't resolve the problem
- Well has difficult access or safety concerns
- You need documentation for real estate transaction
- Iron bacteria or biofilm is present (more aggressive treatment needed)
- You want guaranteed results with follow-up testing
What If Chlorination Doesn't Work?
If bacteria returns after shock chlorination, there's likely an ongoing contamination source:
Common Reasons for Recurring Contamination
- Compromised well seal: Cracks or gaps in the well cap or casing allow surface water entry
- Well casing damage: Corrosion or cracks below ground level
- Shallow well construction: Inadequate depth or grout seal
- Nearby contamination source: Septic system, animal waste, or surface runoff
- Aquifer contamination: The groundwater itself is contaminated
Next Steps After Failed Chlorination
🔍 Investigation Options
Well Inspection
$200 - $500
Visual inspection of well cap, casing, and components
Video Camera Inspection
$300 - $800
Camera down well to check casing integrity
Well Rehabilitation
$2,000 - $8,000
Repair or reline damaged casing
Continuous Treatment
$800 - $2,000
Install ongoing chlorination or UV system
For persistent issues, consider our well video inspection service to identify the contamination source.
Frequently Asked Questions
How much does it cost to chlorinate a well?
Professional shock chlorination costs $150-$500 depending on well depth and system size. DIY costs $20-$50 for materials. Add $30-$100 for recommended follow-up bacteria testing.
How often should I chlorinate my well?
Most wells don't need routine chlorination. Treat only after positive bacteria tests, well work, flooding, extended non-use, or when water quality changes. Annual chlorination isn't necessary for properly constructed wells.
Can I chlorinate my well myself?
Yes, with proper knowledge of your well specifications and safety procedures. You'll need unscented bleach or chlorination tablets, safety equipment, and 24-48 hours without water use. Professional service is recommended if you're unsure.
How long does well chlorination take?
The chlorination process takes 1-2 hours, followed by 12-24 hours of contact time. Flushing takes 2-4 hours. Total time from start to usable water is 24-48 hours.
Will chlorination fix my rotten egg smell?
If the smell is from sulfur bacteria, shock chlorination often eliminates it. If the smell is from sulfur minerals in groundwater, chlorination provides only temporary relief—ongoing treatment may be needed.
Is chlorinated well water safe to drink?
After proper flushing to below 4 ppm (similar to municipal water), yes. During treatment, the highly chlorinated water is NOT safe for drinking, bathing, or plants/animals.
What if bacteria comes back after chlorination?
Recurring contamination indicates an ongoing source—damaged well casing, compromised seal, or nearby contamination. Investigation is needed to identify and address the root cause, or continuous treatment may be required.
Should I test my water after chlorination?
Yes, always retest for bacteria 7-14 days after chlorination. This waiting period allows any surviving bacteria to regrow to detectable levels, confirming whether treatment was successful.
Need Professional Well Chlorination?
Southern California Well Service provides professional shock chlorination throughout San Diego and Riverside counties. We'll properly treat your entire system, verify results with testing, and help identify contamination sources if problems persist.
