Water · Commission the system · water-19

Disinfect and flush the new system

New wells, spring boxes, tanks and pipes pick up dirt and germs during construction. Shock chlorination cleans them before first use.

How

Scrub out tanks and spring boxes and remove debris.
Shock chlorinate to about 200 ppm. NC State gives about 3 pints of 5 percent bleach per 100 US gallons (roughly 1.4 L per 380 L) and a hold time of at least 12 hours.
Use the chlorine dose calculator on this page to scale the 200 mg/L shock dose to your volume and bleach strength.
Run chlorinated water to every tap until you smell chlorine, then hold at least 12 hours.
Flush with fresh water until no chlorine smell or taste remains. Do not flush strong chlorine into a septic system or onto plants.
Wait 24 hours after flushing and take a bacteria sample (NC State).
For wells, the driller usually disinfects after installation; ask for the record.

Safety: Shock chlorine is strong: wear gloves and eye protection, ventilate enclosed spaces, and never mix bleach with acids or ammonia.