Water Tanks, page-67

Enjoy your subject matter keep up the fresh topics. The wood heater one was interesting as well.
I always learn something that's for sure. Constructive discussion is great.

The reason I needed to put some thought into this topic is that we collect water into several tanks off two separate buildings, (total 360 square metres).
These are connected underground then connected to a pump, to move the water 140 metres to a height of 28metres for storage. The line to the storage is wet as well obviously, we have no choice. This is our supply to the house as well, (which is the area where the collection takes place)
In the summer I can isolate the collection tanks from the pipework (collectively or individually) and drain the complete manifold into a dam. This enables isolation or flushing of one or all tanks or the manifolding as required, and eliminates the potential contamination issues on that side, as you have correctly suggested.
On the storage side I have eliminated the potential problems by using only one line to pump the water up into the bottom of the storage tanks as well as to supply the house in the reverse direction. This way the potential anaerobic zone is eliminated at the bottom of each tank, as the fresh water circulates by virtue of being introduced to the bottom of the tanks and the used water leaving from the same place.
This is why I use the sediment traps (one to each collection tank) as I cant afford to have sediment build up in the supply tanks or the wet lines. I have kept the collection tank outlet manifold large, to keep the water speed slow so that it will also act as another sediment trap before the water gets to the transfer pump.
I also did not want t be replacing filter elements (time and cost) which can potentially create bacteria deposits in themselves.
Our total maintenance consists of opening the sediment traps and opening the drain valve on the collection manifold prior to a dry spell, and adding lime occasionally as required.