Hydrometer on the fritz? Super attenuation?

I'm going crazy here trying to determine if I have super attenuation or if my hydrometer is simply not calibrated well. The saison you see above should have finished at 1.002 but the hydrometer reading indicates something more along the line of .992 a difference of .010 (OG 1048 French Saison Yeast 16.7% Turbinado sugar Been cruising along with no temp control Went past 78*F now its down to 70). The stout should have finished around 1.018 (OG 1.064 Safale s-04 yeast 66*F 4days fermentation 70*F conditioning 7 days). Lately I've been getting some crazy low OG for my beers indicating rather poor efficiency. However at the same time when I put the hydrometer in tap water it was almost right on the mark 1.000. The water was cold so I know the gravity reading should have been a little higher than 1.000 but I don't think it was enough change the gravity much at all. Neither or these beers taste like it has an infection or anything. They do not taste overly dry the stout actually came out sweeter than i thought it would. I am genuinely confused. Does anyone have an idea whats going on here?

 

Sorry I forgot to mention this but my water is very soft, 2.1 ppm Ca .5 ppm Mg 6.3 ppm Na 4.1 ppm SO4 9 ppm cl 4.4 ppm HC03.
I thought that these low ion concentrations wouldn't be enough to throw it off that much but I could very well be wrong.