What is a good source for large tables on the properties of water? I'm currently doing an investigation for school on finding the Clausius-Clapeyron relation/gradient for  boiling water and comparing it to the gradients along my line of best fit. It is given by the equation,
$$
\frac{\text{d}P}{\text{d}T} = \frac{L}{T\Delta v}.
$$
I'm having trouble finding the specific volume of both water and steam (I found this for water but I'm not sure of the credibility) for $\Delta v$. I was hoping someone could reference me to a large data table for finding the specific volume, or a calculator. Thank you.
Such values for various properties of liquid water and steam can be looked up in so-called steam tables. Software versions also allow calculations (ususally interpolation) of additional values. For example, I usually use REFPROP – NIST Standard Reference Database (however, not always the latest version) or some old and simple proprietary steam table software from Siemens/KWU.

If you do not have access to professional steam tables, you may want to consider using the steam tables that are included in WolframAlpha.