Safety first: work outdoors or with the wellhead cover open, wear gloves and eye protection, and never mix bleach with any other cleaning chemical. Run every faucet in the house until you smell chlorine, then let the system sit for at least 12 hours before flushing the lines outdoors (away from septic systems and vegetation) until the chlorine smell is gone. If contamination persists after shock treatment, have your water professionally retested and consult a licensed well contractor.