Try a Chlorine Flush
Our water system is nearly identical to the one you describe: 50 micron filter, 10 micron filter, carbon filter, UV sterilizer. Our water test by the state lab showed no coliform bacteria.
Before I put our system in use, I put about a half cup of chlorine into the sump of the 3rd filter (where the carbon one normally goes) and ran all the taps and showers at once until they smelled of chlorine. Then I let things sit for at least an hour and ran everything again until there was no smell.
I don't think this kind of one-time treatment hurts the septic system.
I think this is also good for the water in the hot water heater. I know you are not taking a hot water sample, but I am concerned about showering in water that has bacteria.
I agree with another post that said you probably have some contamination in the pipes downstream of the UV filter. Assuming that your UV chamber is working properly, you would not have bacteria on the test.
(Did you remove the faucet screen where you took the water sample? Apparently they can harbor bacteria.). Also, I think you should run the faucet for several minutes before taking the sample.
I think you could repeat this process every year or two without harming your septic system.
|