i have installed a water harvesting system for my mobile home
and its in north conuty dublin, ireland so no shortage of rain fall!!!
i'm looking to build a simple water filter system... this rain water will be used for shower and washing dishes so doesnt need to be drinking level filtration....
A very simple filter is this sand filter.The rain falls into the right side, and gravity takes it into the sand. The water will seek the same level in each side (as long as they are both vented). If you wanted to convert this for a better quality water, simply add charcoal to the left side, so that the sand filtered water now needs to pass through the charcoal to get to the outlet.
The same effect could be had with two barrels connected by a pipe near the bottom. Just make it shallow enough that you can change out the sand periodically.