Cleaning 5 yr old water in system
I'm getting ready to visit my cabin that's been unused for about 5yrs so I'm sure my water tank and pipes have some stagnant water in them. I'm wondering how I should clean them out.
Here's a list of what needs to be flushed out. The water supply is a spring with a 20 gallon collection tub, this will remain as is since it always has running water in it. There's a 1 inch plastic pipe that's buried 3ft and goes from the spring, down the canyon for 1/2 mile and the other side for another half mile, emptying into a 2,000 gallon tank that sits about 20ft below the level of the spring, so it's gravity feed. At the bottom of the canyon are a set of valves so I can clean out the sediment that collects in the pipe line. From the 2k gallon holding tank it goes to a pump/softener and then to my house.
I'd like to clean all these pipes out. I'm sure the water 1 mile of pipe has been sitting there for over 4 yrs since the sediment blocks the pipe after 1 yr or so. So I'm thinking that once I get the water flowing again and fill up the holding tank, I should run clean water through all the pipes. But I'm also thinking I should put a couple gallons of chlorine bleach in the holding tank, water softener, all the pipes in the house, and the 1 mile of buried pipe and let it sit for 12 hours. My only concerns are that the chlorine might not be good for my septic tank and when I drain the 2k gallon holding tank, all that chlorine would go down the hillside which probably isn't that great for the environment. Is there something safer I can use than chlorine or should I not even worry about doing that, just run fresh water through the pipes and forget about it.