Why does sulphur smell linger so long after treating it?

Question

My chlorine injector stopped working a couple weeks ago and I had it fixed.

After three days of normal use by a family of 5, I tested the water coming out of the 120Gal treatment tank and it smelled like chlorine. Not ideal, but it means the sulphur is completely neutralized within the tank. I can adjust my injector pump to reduce the chlorine, and there is a carbon filter downstream that extracts the excess.

After that I ran water out of the shower and faucet furthest from the pump for 20 minutes. Then I ran water from a stationary tub fairly near the pump. It started to smell slightly better, but maybe my nose was getting used to it.

In any event, I am wondering why the water still smells so strong since I estimate I ran 200 gallons of water through the carbon, softener and pipes. After 2 weeks and paying the water company I am tired of answering the complaints! It never took this long in the past when I had to replace the duckbill valve or the systolic tube.

Answer 1

The root cause was not residual sulphur in the pipes.

I found out that there were, in fact two contributing problems to begin with: one was obvious and not root cause (a blockage at injector site) and one was subtle and true root cause.

The true root cause was the bearing wear in the injector pump. This caused the vertical pinch rollers to become canted in a slightly cone formation. The systolic pump tube found its way to the loosest part of the rollers, which was at the bottom. Over several years, an increasing amount of chlorine could escape from the pinched area away from the injector back to the reservoir as the wear increased. Eventually it reached the point where it no longer pumped enough to treat the sulphur.

So, if you are reading this due to a similar problem and you have a Stenner pump with vertical pinch rollers in a clear housing - check the position of the pinch tube. If it is not in the center, you might need to replace the roller housing.

Answer 2

Sulfur adheres to minerals and (generally harmless) sulfur- and iron-metabolizing bacteria that can coat the inside of pipes. It's not unreasonable that it took some time to eliminate the sulfur not only from the tanks, but also to flush the layers inside pipes.

Perhaps just letting the chlorinated water sit in the plumbing for a day would have worked almost as fast, as the free chlorine reacts with the layer holding the sulfur.

Answer 3

You might need to remove or bypass the carbon filter and get chlorine into all the pipes for a while - then re-install the carbon filter and flush it out.