Since I had the reverse osmosis system laid out for assembly, I figured I could take a picture to show how the filters are connected in series. Each filter “cleans” water out of the maple sap — that water is fed into a common output tube where we collect gallons of water (the clean water output lines are removed here so we can see the path maple sap travels, ignoring the clean water). We use this water for rinsing sappy stuff as we collect, filter, and boil the sap … also water we drink, bring out to the chickens and turkeys, give the cat, dump in the washer.
The “dirty stuff” that normally gets discarded? That’s the concentrated sap — each filter’s “dirty stuff” line is connected to the input of the next filter. Which then “cleans” more water from the sap and passes the “dirty stuff” down the line.
The maple “setup” is the reverse of the “drinking water” setup — below — where the “dirty stuff” goes to a common drain line for disposal and the clean water is sent to the input of the next filter for farther cleaning.