Four readings, one ratio
Make-up water, cleaning water, drain volume and saleable weight. The first two add up to what came out of the tap, the last one is what left the building, and the ratio between them is the whole page. With the defaults it is 1,780 gallons against 676.8 lb sold, which is 2.63 gallons a pound or 21.9 litres a kilogram.
The drain figure does not go into the ratio. It goes into the split: make-up minus drain is what left as vapour or in the crop, which with the defaults is 1,260 gallons over 28 days, or 45 gallons a day. That is a transpiration figure derived by difference, and it is worth comparing against whatever a scale or a reservoir sight glass says, because when the two disagree one of the meters is lying.
Cleaning water is the reading nobody takes
It is 180 gallons in the defaults, which is 10 percent of everything drawn, and in a room that washes trays properly it is often much more. It never appears in a published water-use figure because it is not part of the growing system, and it is real water on a real bill. Any comparison that leaves it out is comparing a growing system with a farm, which is not the same thing as comparing two farms.
About the baseline
The baseline field is deliberately empty of authority. Whatever number you put in it came from a source you chose, and this page does not supply one, endorse one or know whether it is comparable. The things that most often make it not comparable are worth listing: whether rainfall counts as water use, whether field losses to evaporation and runoff are included, whether the figure is per harvested weight or per saleable weight, whether post-harvest washing is in it, and what crop, climate and season it was measured in.
A ratio of 10 percent against a field baseline sounds decisive and means very little without those answers. The number the page is actually good for is the one it gives without any baseline at all: your own litres per kilogram, measured the same way every month, moving up or down.
What stops at the meter
Water in the nutrients, in the media, in the packaging. Water used to generate the electricity, which for an indoor farm running fixtures sixteen hours a day is not a rounding error in any full accounting. Condensate off the cooling coils, which if it is returned to the reservoirs shows up as a lower make-up reading and if it is not returned never appears at all. This page counts what the meter counts and says so.
Questions people ask
Should I use harvested weight or saleable weight?
Saleable, which is why the cull share is a field. Water spent growing something that got thrown away is still water spent, so it stays in the numerator while the culled weight leaves the denominator. That makes the figure worse than a harvested-weight figure would, and it is the more honest of the two. Just make sure any baseline you compare it against is on the same footing.
Why is the drain volume not in the ratio?
Because it is already inside the make-up reading. Water that went to drain was metered in first, so counting it again would double it. The drain figure is used only to split the make-up water into what left as vapour and what left as liquid, which is a useful check against a scale or a sight glass reading.
What period should I measure over?
A whole number of crop cycles, rather than a calendar month. A reservoir change landing inside the window adds a large slug of drain volume that belongs to a longer period, and a month that happens to contain two changes reads very differently from one that contains one. Twenty-eight days on a 28 day crop is clean.
Where do I get a baseline figure?
That is yours to choose and yours to cite. This page supplies no comparison figure and takes no position on any published one. If you use one, write down the source, the crop, the region and what it includes, because those four things decide whether the comparison means anything at all.
Does recovered condensate count?
Only indirectly. If condensate off the cooling coils goes back into the reservoirs, the make-up meter reads lower and the water per kilogram figure falls, which is correct — that water genuinely was not drawn from the tap. If it goes down the drain it never touches this calculation. Either way the page counts what the meter counted.