The home food computer will need to be easy to fill/refill the water and flush the gray water out of. I was thinking of a design like this. It can leverage components sourced on Amazon, and can piggy back on the 12V power scheme of the FC1.0 design.
if the water line is 1/2 inch, then the left over black tubing purchased already can be leveraged as well. The solenoids cost around 14$, cheaper may be able to be found if we search hard enough. The fittings are around 5-6$.
Water sensors could be drilled into the sides at various heights. This could give you a sense of how much water has been drained and how much has been filled. These sensors are around 10-15$.