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Well Disinfection
(Shock Chlorination)

Shock chlorination is a common way to disinfect a private well after pump work, repairs, or suspected bacterial contamination. This page shares a practical checklist and a downloadable PDF you can refrence.

Quick safety notes (please read first)

  • Do not drink, cook with, bathe, or wash with the water until chlorine is fully purged and you’ve confirmed safe water (use test strips; retest if needed)

  • Use the right test strips: one that can read full-range chlorine (0 – 500 ppm)

  • Protect your septic + environment: discharge chlorinated water away from your septic system, landscaping, and any waterways—never into a storm drain, ditch, creek, or pond.

  • Electrical safety: wells combine water + electricity. If you’re not confident working safely around the well cap/pump wiring, stop and call a licensed well contractor

  • Do not exceed 36 hours of contact time (high chlorine can be corrosive to metals and components).

When to use shock chlorination

  • After well pump replacement or well service work

  • After a positive coliform/E. coli result (follow local guidance)

  • After flooding, well cap damage, or suspected surface intrusion

  • When advised by a licensed well contractor

What this process covers

  • Disinfecting the well + plumbing

  • Contact time

  • Purging chlorine safely

  • Post-disinfection testing timeline

Download the checklist (PDF)

Key steps (plain-English summary)

  • Bypass treatment equipment

  • Calculate dose (100 ppm standard; 170 ppm for iron/slime/SRB)

  • Add tablets/pellets

  • Circulate and verify concentration with strips

  • Pull chlorinated water into all fixtures/appliances

  • Let sit 12–24 hours (do not exceed 36)

  • Purge to safe discharge area; protect septic

  • Verify 0 ppm (or as close as practical) at farthest fixtures

  • Replace filters / return equipment to service

  • Test water 2–3 weeks later

FAQs

  • How much chlorine do I need for 100 ppm?

  • How long should it sit?

  • Can I flush into my septic?

  • Why does water look discolored during purging?

  • When should I test again?

Need help?

If you’re planning well work (or you’ve just had a pump replaced) and you want to be confident the disinfection and chlorine purging were done correctly, I’m happy to help. Start with my Well Water Self-Check for quick guidance, or schedule a Healthy Home Evaluation for clear answers based on real testing—so you’re not stuck guessing or chasing the wrong fix.

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Questions about the Shock Chlorination Process?

Email: info@healthywellwater.com or call (303) 948-1706 for friendly, expert advice and solutions.

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