Animals in the well? We have you covered.

This post explains why animal and insect intrusion happens, why simple chlorination is often not enough, and how to properly treat a contaminated well using a proven cleaning and disinfection process, including the use of Cotey Chemical’s Welgicide® well cleaner.

Why Animals and Insects Get Into Wells

Intrusion usually occurs due to structural or maintenance issues, such as:

• Missing or non-sanitary well caps

• Cracked or corroded well casing

• Improper seals around electrical conduit

• Flooding or surface water intrusion

• Older wells with pit-style or loose covers

Common intruders include rodents, frogs, snakes, insects, birds, and occasionally bats. Once inside, these organisms may die, decompose, and most certainly leave waste behind—creating ideal conditions for bacterial growth.

Why This Is a Serious Health Concern

Animal and insect contamination can introduce:

• Total coliform bacteria and E. coli

• Giardia and Cryptosporidium

• Salmonella and other pathogens

• Organic nutrients that fuel biofilm growth

Decomposing organic matter also consumes chlorine, reducing its effectiveness. This is why many wells test positive for bacteria again shortly after shock chlorination.

Without proper cleaning, disinfection alone is often unsuccessful.

Step-by-Step: How to Properly Treat a Contaminated Well

1. Remove the Source of Contamination

• Remove dead animals or visible debris

• Flush loose material from the well

2. Repair and Secure the Well

Before treatment:

• Install a sanitary, vermin-proof well cap

• Seal casing cracks or openings

• Ensure the casing extends at least 12 inches above grade

• Grade soil to divert surface water away from the well

Failing to correct entry points will lead to repeat contamination.

3. Clean the Well Using Cotey Chemical’s Welgicide® (Critical Step)

When animals or insects enter a well, they leave behind organic residue and biofilm that protects bacteria from disinfectants. This is where a dedicated well cleaner is essential.

Cotey Chemical’s Welgicide® well cleaner is specifically designed to:

• Break down organic matter from insects, animals, and waste

• Penetrate and loosen biofilm on casing, pump components, and formation surfaces

• Improve the effectiveness of subsequent disinfection

Welgicide® is circulated throughout the well to chemically clean surfaces that brushing or flushing alone cannot reach. This step dramatically increases the success rate of disinfection and reduces the likelihood of recurring bacterial problems. See: https://www.coteychemical.com/products/welgicide-cleaner/ for more information.

4. Disinfect the Well After Cleaning

Once the well has been properly cleaned:

• Apply a calculated chlorine dose of Cotey Chemical’s WelChlor PLUS

• Circulate through the entire system (well, pressure tank, plumbing)

• Allow adequate contact time (typically 12–24 hours)

Because Welgicide® removes organic demand and biofilm, the disinfectant can now contact and kill bacteria effectively. See: https://www.coteychemical.com/products/wel-chlor/ for more information

5. Flush and Neutralize

After disinfection:

• Flush until chlorine levels are safe

• Remove residual tastes and odors

• Dispose of chlorinated water away from septic systems and vegetation and any bodies of water

6. Test the Water

• Test for total coliform and E. coli

• Repeat treatment only if necessary

Preventing Future Animal and Insect Intrusion

• Install and maintain a sanitary well cap

• Inspect the well annually

• Keep the area around the well clean and well-drained

• Test water regularly, especially after flooding

Prevention is far easier—and less costly—than remediation.

Final Thoughts

Animals and insects in a water well create persistent contamination risks that cannot be solved by chlorine alone. Proper cleaning with a product like Cotey Chemical’s Welgicide®, followed by disinfection using WelChlor PLUS and testing, is the most reliable way to restore water safety.

Address both the contamination and its cause, and your well can continue providing clean, dependable water for years to come.