How to determine if well pressure tank needs replacing?

Question

We have found colorform bacteria in our well water system. Problem has been isolated to rule out bacteria in the well itself. We have chlorinated the well twice. Still have bacteria near pressure tank area. Pressure tank air valve on top does not leak water when pushed, only air, so conclude that tank is fine. Does it need replacing (because it might have bacteria growing in it)? We went ahead and poured chlotine all around the pressure tank area and pipes, faucets, etc.

Main question is should I purchase a new pressure tank if it is not showing water when the top valve for air is pushed? Does this mean the bladder is not broken to allow bacteria to hide? When we chlorinated twice the water that went in the pressure tank was chlorinated. left it almost 24 hours each time.

Answer 1

If the pressure tank isn't showing signs of a problem such as short cycling, pulsating water pressure, or water pressure gauge rapidly oscillating from high to low pressure then the bladder in the tank is probably o.k.  Did you verify that the bladder in your pressure tank could be exposed to chlorine? If not then it may fail prematurely sometime soon.

Did you drain out as much water from your system as possible, including hot water tanks and the pressure tank before adding the disinfectant?   Did you calculate the correct volume of your water system and well in order to make sure you used enough disinfectant?  Did you bypass or remove any activated carbon filters from the system siince they will remove the chlorine (until they become overloaded) and not let it circulate through the remaining parts of the system?  

In a bladderless tank system you would actually need to drain down the tank and refill it with chlorinated water to fully disinfect it.  In a bladder tank system you would still want to drain it down as much as possible before refilling the system with disinfectant.

If not then you may not have gotten sufficient disinfectant into the system or allowed it to flow into all the points within the system to be completely effective.

When you say that you poured chlorine all around the tank area, pipes, etc. do you mean to poured it into the water in the pipes or just around the outside of them?  Pouring chlorine around the outside of them won't disinfect inside the pipes, but it may damage the outside of them that could lead to leaks.

I assume you have made sure the well head area is clean and free of any openings that could allow stuff to get into the well.  It it possible that something (like a mouse) could have gotten sucked into the water line and become lodged in a valve or fitting so that after the disinfectant is flushed out it recontaminates the line?  I'm not how to check this other than making sure everything is wide open and trying to fish a plumber's tape through the valves and fittings.