  We present 5.5 to 7.6 micron spectra of comets 71P/Clark (2006 May 27.56 UT,
r_h = 1.57 AU pre-perihelion) and C/2004 B1 (LINEAR) (2005 October 15.22 UT,
r_h = 2.21 AU pre-perihelion and 2006 May 16.22 UT, r_h = 2.06 AU
post-perihelion) obtained with the Spitzer Space Telescope. The nu_2
vibrational band of water is detected with a signal-to-noise ratio of 11 to 50.
Fitting the spectra using a fluorescence model of water emission yields a water
rotational temperature of < 18 K for 71P/Clark and approximately less than or
equivalent to 14 +/- 2 K (pre-perihelion) and 23 +/- 4 K (post-perihelion) for
C/2004 B1 (LINEAR). The water ortho-to-para ratio in C/2004 B1 (LINEAR) is
measured to be 2.31 +/- 0.18, which corresponds to a spin temperature of
26^{+3}_{-2} K. Water production rates are derived. The agreement between the
water model and the measurements is good, as previously found for Spitzer
spectra of C/2003 K4 (LINEAR). The Spitzer spectra of these three comets do not
show any evidence for emission from PAHs and carbonate minerals, in contrast to
results reported for comets 9P/Tempel~1 and C/1995 O1 (Hale-Bopp).
