Why is shock chlorinating important?
Because shock chlorinating, which involves siphoning a specific, highly concentrated chlorine solution into your well, is (currently) the best way to kill most of the pathogenic and nuisance bacteria in it. If performed regularly—usually, annually—it’s the best way to keep your well and water safe.
Pathogenic bacteria (like E. Coli) are harmful or potentially harmful to humans; they show up as “coliform forming units” on lab results. Nuisance bacteria are the iron- and sulphate-reducing types (that is, the types that feed on iron and sulphate present in water). They aren’t harmful, but they cause issues: they can plug up your well with biofilm, stain your toilets and showers, and make your water smell like rotten eggs.
Biofilm build up on a drop pipe.
Biofilm build-up on a pitless adapter.
A shock chlorination in progress.
How long does shock chlorinating take?
It will only take us about an hour to apply the chlorine solution to your system. But after that, the solution needs to sit in your system for a minimum of 12 hours. (Ideally, it should sit for 24 hours: the longer the solution sits, the deeper it can penetrate any biofilm present inside the well. After that, you’ll flush your system, which can take anywhere from 1 hour to 24 hours.
From start to finish, then, shock chlorinating can take anywhere from (roughly) 14 to 49 hours. We’ll be able to give you a more specific estimate once we know the specifics of your system.
Will I have access to my water during this time?
No. Once treatment has begun, you won’t have access to your water until the solution has been flushed completely from your system. In other words, you won’t be able to turn on your taps for a period of time. Why? Because 1) it takes time for the solution to do its bacteria-killing work and 2) you don’t want the solution to destroy the good microbes in your septic system.
You can use your toilets, if you use water from an outside source. We usually advise clients to fill their tub/s with water before treatment begins, so they can use that water to “flush” their toilets.
What does “flushing my system” look like?
Flushing is easy. You’ll go to an outside tap, position the hose away from your home and vegetation, and turn on the tap (at a specific rate, so as not to over-pump the well).
At some point, you might see orange or black sediment come out of the tap—that’s the biofilm build-up that the chlorine solution dislodged. You want this to be purged from your system.
How will I know how long to flush my system for?
Don’t worry: Essential Water Works will give you guidance here. Basically, the time required to clear your system of chlorine will depend on the depth of your well, the well’s yield, and the volume of chlorinated water used.
How often should my well be shock chlorinated?
Of course, if a recent water quality test results indicate pathogenic bacteria in your well, you should have your system treated immediately.
Generally, though, you should plan to have your well shock chlorinated annually, preferably in the early Spring (in April or May). You want to shock chlorinate annually because, over time and for various reasons, pathogenic and/or nuisance bacteria may re-enter your system. And you want to shock chlorinate in the early Spring to disinfect any contamination brought about by winter rains and run-off.