40L = 40 kilos
(of water, or course)
My old day pack was a heavy 30L (3.5-3.8 ish#s MT)
Now have an ultra light 24L that is soo much easier to deal with and I schlep around less stuff.
This will not hold much if it’s only 40L, but may be perfect for a closet shelf and sorting items.
Or under the bed for extra shoes?